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revng-revng/lib/Lift/CPUStateAccessAnalysisPass.cpp
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Ivan Krysak 7d235f4fd0 Enforce licence header consistency 
Also do some basic cleanup: capitalize first letters, add `.`
at the end of the sentences, and so on.
2023-07-03 15:23:10 +00:00

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/// \file CPUStateAccessAnalysisPass.cpp
/// This file performs an analysis for reconstructing the access patterns to the
/// CPU State Variables (CSV).
//
// This file is distributed under the MIT License. See LICENSE.md for details.
//
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/raw_ostream.h"
#include "revng/Support/Debug.h"
#include "revng/Support/IRHelpers.h"
#include "CPUStateAccessAnalysisPass.h"
#include "VariableManager.h"
namespace llvm {
class DataLayout;
}
using namespace llvm;
using std::optional;
using ConstFunctionPtrSet = std::set<const Function *>;
using InstrPtrSet = llvm::SetVector<Instruction *>;
using CallPtrSet = std::set<CallInst *>;
using ConstValuePtrSet = std::set<const Value *>;
/// Logger for forwardTaintAnalysis
static auto TaintLog = Logger<>("cpustate-taint-analysis");
/// Logger for the creation of WorkItem
static auto CSVAccessLog = Logger<>("cpustate-access-analysis");
/// Logger for fixing the accesses to CPUState
static auto FixAccessLog = Logger<>("cpustate-fix-access");
static uint64_t NumUnknown = 0;
static std::map<std::string, uint64_t> FunToNumUnknown;
static std::map<std::string, std::set<std::string>> FunToUnknowns;
/// Computes the set of Functions reachable from a given Function through direct
/// calls.
///
/// \param RootFunction is a pointer to the Function from which is the
/// starting point for computing reachability.
/// \param LoadMDKind is the metadata kind used for decorating call sites that
/// access CPU State to load data
/// \param StoreMDKind is the metadata kind used for decorating call sites that
/// access CPU State to store data
/// \param Lazy tells if the analysis is running in Lazy mode
/// \return set of pointers to the reachable Functions
///
/// This function can probably be implemented using the call graph utilities
/// already present in LLVM, but when I tried it I spent a day doing it and I
/// gave up because of bugs in the functions coming from LLVM. Then I
/// implemented my own version, i.e. this function
static ConstFunctionPtrSet
computeDirectlyReachableFunctions(const Function *RootFunction,
const unsigned LoadMDKind,
const unsigned StoreMDKind,
const bool Lazy) {
std::map<const Function *, ConstFunctionPtrSet> CallGraph;
const Module &M = *RootFunction->getParent();
// Initialize empty CallGraph
for (const Function &F : M)
CallGraph[&F] = {};
for (const Function &F : M) {
for (const Use &U : F.uses()) {
const User *TheUser = U.getUser();
if (const auto *TheCall = dyn_cast<const CallInst>(TheUser)) {
// If this call has already been decorated with LoadMDKind or
// StoreMDKind metadata it means that it has already been processed by
// a previous run of CPUStateAccessAnalysis.
// If we're running in lazy mode, we can skip calls that have already
// been decorated.
if (Lazy) {
if (TheCall->getMetadata(LoadMDKind) != nullptr
or TheCall->getMetadata(StoreMDKind) != nullptr) {
continue;
}
}
const Function *Caller = TheCall->getFunction();
const Function *Callee = getCallee(TheCall);
if (Callee == &F) {
CallGraph[Caller].insert(Callee);
}
} else if (const auto *CExpr = dyn_cast<const ConstantExpr>(TheUser)) {
SmallPtrSet<const ConstantExpr *, 16> CurBitCasts;
SmallPtrSet<const ConstantExpr *, 16> NextBitCasts;
CurBitCasts.insert(CExpr);
while (not CurBitCasts.empty()) {
NextBitCasts.clear();
for (const ConstantExpr *BitCast : CurBitCasts) {
for (const User *BitCastUser : BitCast->users()) {
const auto *TheCall = dyn_cast<const CallInst>(BitCastUser);
const auto *NewCExpr = dyn_cast<const ConstantExpr>(BitCastUser);
if (TheCall) {
// If this call has already been decorated with LoadMDKind or
// StoreMDKind metadata it means that it has already been
// processed by a previous run of CPUStateAccessAnalysis.
// If we're running in lazy mode, we can skip calls that have
// already been decorated.
if (Lazy) {
if (TheCall->getMetadata(LoadMDKind) != nullptr
or TheCall->getMetadata(StoreMDKind) != nullptr) {
continue;
}
}
const Function *Caller = TheCall->getFunction();
const Function *Callee = getCallee(TheCall);
if (Callee == &F) {
CallGraph[Caller].insert(Callee);
}
} else if (NewCExpr) {
NextBitCasts.insert(NewCExpr);
}
}
}
std::swap(CurBitCasts, NextBitCasts);
}
}
}
}
ConstFunctionPtrSet ReachableFunctions = { RootFunction };
ConstFunctionPtrSet CurrentChildren = { RootFunction };
ConstFunctionPtrSet NextChildren;
while (not CurrentChildren.empty()) {
NextChildren.clear();
for (const Function *F : CurrentChildren) {
for (const Function *Callee : CallGraph.at(F)) {
bool NewInsertion = ReachableFunctions.insert(Callee).second;
if (NewInsertion)
NextChildren.insert(Callee);
}
}
std::swap(CurrentChildren, NextChildren);
}
return ReachableFunctions;
}
struct TaintResults {
// A set of Instructions that access the CSV to load data. They can be
// LoadInst or CallInst to Intrinsic::memcpy for which the size is known.
InstrPtrSet TaintedLoads;
// A set of Instructions that access the CSV to store data. They can be
// LoadInst or CallInst to Intrinsic::memcpy for which the size is known.
InstrPtrSet TaintedStores;
// A set of Values that are tainted during the analysis.
ConstValuePtrSet TaintedValues;
// A set of CallInst that are considered illegal. These include indirect
// calls, calls to functions without body, and calls to Intrinsinc::memcpy
// with unknown size. They are considered illegal because we have no way of
// knowing how they access the CSV.
CallPtrSet IllegalCalls;
bool empty() const noexcept {
return TaintedLoads.empty() and TaintedStores.empty()
and IllegalCalls.empty();
}
};
/// Interprocedural forward taint analysis.
//
/// \param CPUStatePtr is a pointer to the CPU State Variable, which is a global
/// variable. This variable is the Value that taints all the others.
/// \param ReachableFunctions is a set of functions that are reachable from
/// the root function. The analysis is restricted to those functions.
/// \param LoadMDKind is the metadata kind used for decorating call sites that
/// access CPU State to load data
/// \param StoreMDKind is the metadata kind used for decorating call sites that
/// access CPU State to store data
/// \param Lazy tells if the analysis is running in Lazy mode
/// \return a TaintResults containing information on:
/// 1) a set of instructions that access the CSV to load data;
/// 2) a set of instructions that access the CSV to store data;
/// 3) a set of illegal calls, for which it is impossible to understand
/// if and how they will access the CSV.
static TaintResults
forwardTaintAnalysis(const Module *M,
Value *CPUStatePtr,
const ConstFunctionPtrSet &ReachableFunctions,
const unsigned LoadMDKind,
const unsigned StoreMDKind,
const bool Lazy) {
//
// Interprocedural Forward Taint Analysis
//
// This analysis aims to understand all the Values that are affected by the
// CPUStatePtr pointer, that points to the CPUStateVariables (CSVs).
// The main idea is that we explore the use chains depth first, propagating
// interprocedurally when we find a Use whose User is a CallInstr.
//
// The function is structured as follows:
// 1. Iterate on the users of `CPUStatePtr`
// 2. For each user of `CPUStatePtr`, consider its next user,
// building a WorkList of `Use`s in exploration
// 3. If we find unexplored uses keep pushing them on the WorkList. If we
// find a Load or a Store we taint it and don't push anything on the
// WorkList. If it's not a Load or Store we mark it as tainted separately
// 3(a) If the next `Use` to explore is a `CallInst` the taint is
// propagated interprocedurally to the callee, through the arguments
// (propagation from caller to callee)
// 3(b) If the next `Use` to explore is a `RetInst` the taint is
// propagated interprocedurally to the Function.
// (propagation from the callee to all call sites)
// 4. If we didn't push anything on the WorkList we can start exploring the
// other `Use`s of the item that is currently on top of the WorkList
// 5. If we didn't push anything on the WorkList we can start popping `Use`s
// from the WorkList, until we reach a `Value` that still has unexplored
// `Use`s
// 5(a) If we're popping an argument of a function this means that we've
// finished analyzing the uses of that argument. We have to make sure
// that, if the taint reached the return instructions in the function,
// the taint is propagated to the call sites.
// 6. After popping the top of the WorkList in 5., if the new top of the
// WorkList still has unexplored uses start to explore them.
TaintResults Results;
std::set<std::pair<const Function *, const Argument *>>
FunctionArgTaintsReturn;
revng_assert(CPUStatePtr != nullptr);
revng_assert(CPUStatePtr->getType()->isPointerTy());
struct CallSiteInfo {
const CallInst *CallSite;
const Argument *Arg;
const unsigned ArgNo;
CallSiteInfo(const CallInst *C, const Argument *A, const unsigned N) :
CallSite(C), Arg(A), ArgNo(N) {}
};
if (TaintLog.isEnabled()) {
TaintLog << "MODULE:" << DoLog;
TaintLog << dumpToString(M) << DoLog;
}
// 1. Iterate on the users of `CPUStatePtr`
std::set<const LoadInst *> Loads;
{
std::queue<const User *> WorkList;
for (const User *U : CPUStatePtr->users())
WorkList.push(U);
while (not WorkList.empty()) {
const User *U = WorkList.front();
WorkList.pop();
if (auto *CE = dyn_cast<ConstantExpr>(U)) {
if (CE->isCast()) {
for (const User *UCE : CE->users()) {
WorkList.push(UCE);
}
}
} else if (auto *Load = dyn_cast<LoadInst>(U)) {
Loads.insert(Load);
} else {
revng_abort("Unexpected user");
}
}
}
for (const LoadInst *Load : Loads) {
// During the analysis we keep two stacks.
// ToTaintWorkList is a stack representing the Values currently enqued that
// must be tainted and for which we still have to analyze the uses.
// CallSites is a stack representing the CallInst that we entered for
// interprocedural propagation.
std::stack<const Use *> ToTaintWorkList;
std::stack<CallSiteInfo> CallSiteInfos;
// Sanity check for the uses of CPUStatePtr.
// They must all be direct Loads from CPUStatePtr.
revng_assert(Load->getPointerOperand()->stripPointerCasts() == CPUStatePtr);
// Push the first use on the WorkList
const Function *F = Load->getFunction();
if (Load->getNumUses() != 0 and ReachableFunctions.contains(F)) {
if (TaintLog.isEnabled()) {
TaintLog << "Tainted origin: " << Load << DoLog;
TaintLog << dumpToString(Load) << DoLog;
TaintLog.indent();
}
ToTaintWorkList.push(&*Load->use_begin());
}
// 2. For each user of `CPUStatePtr`, consider its next user,
// building a WorkList of `Use`s in exploration
while (not ToTaintWorkList.empty()) {
const Use *TheUse = ToTaintWorkList.top();
revng_assert(TheUse != nullptr);
auto *TheUser = cast<Instruction>(TheUse->getUser());
const auto OpCode = TheUser->getOpcode();
if (TaintLog.isEnabled()) {
TaintLog << "Inst: " << TheUser << DoLog;
TaintLog << dumpToString(TheUser) << DoLog;
}
const size_t Size = ToTaintWorkList.size();
// 3. If we find unexplored uses keep pushing them on the WorkList. If we
// find a Load or a Store we taint it and don't push anything on the
// WorkList. If it's not a Load or Store we mark it as tainted separately
// This switch explores the use-chains depth-first, pushing unexplored
// uses on the ToTaintWorkList if necessary.
unsigned OperandNo = TheUse->getOperandNo();
switch (OpCode) {
case Instruction::Load: {
TaintLog << "LOAD" << DoLog;
revng_assert(OperandNo == LoadInst::getPointerOperandIndex());
auto *L = cast<LoadInst>(TheUser);
if (TheUse->get() == L->getPointerOperand()) {
if (TaintLog.isEnabled()) {
TaintLog << "TAINT: " << TheUser << DoLog;
TaintLog << dumpToString(TheUser) << DoLog;
}
Results.TaintedLoads.insert(TheUser);
}
} break;
case Instruction::Store: {
TaintLog << "STORE" << DoLog;
revng_assert(OperandNo == StoreInst::getPointerOperandIndex());
auto *S = cast<StoreInst>(TheUser);
if (TheUse->get() == S->getPointerOperand()) {
if (TaintLog.isEnabled()) {
TaintLog << "TAINT: " << TheUser << DoLog;
TaintLog << dumpToString(TheUser) << DoLog;
}
Results.TaintedStores.insert(TheUser);
}
} break;
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
case Instruction::BitCast:
case Instruction::IntToPtr:
case Instruction::PtrToInt:
case Instruction::GetElementPtr:
case Instruction::PHI:
case Instruction::Add: {
TaintLog << "OP" << DoLog;
auto OperandId = GetElementPtrInst::getPointerOperandIndex();
revng_assert(OpCode != Instruction::GetElementPtr
or TheUse->getOperandNo() == OperandId);
// Taint TheUser, and if this is the first time we taint it we also push
// on the ToTaintWorkList its first use that is not tainted
bool JustTainted = Results.TaintedValues.insert(TheUser).second;
if (TaintLog.isEnabled()) {
TaintLog << "TAINT: " << TheUser << DoLog;
TaintLog << dumpToString(TheUser) << DoLog;
}
if (JustTainted) {
TaintLog << "Just Tainted" << DoLog;
for (const Use &U : TheUser->uses()) {
TaintLog << "User: " << U.getUser() << DoLog;
if (!Results.TaintedValues.contains(U.getUser())) {
TaintLog << "PUSH" << DoLog;
ToTaintWorkList.push(&U);
TaintLog.indent();
break;
}
}
}
} break;
case Instruction::Call: {
TaintLog << "CALL" << DoLog;
auto *TheCall = cast<CallInst>(TheUser);
// If this call has already been decorated with LoadMDKind or
// StoreMDKind metadata it means that it has already been processed by
// a previous run of CPUStateAccessAnalysis.
// If we're running in lazy mode, we can skip calls that have already
// been decorated.
if (Lazy) {
if (TheCall->getMetadata(LoadMDKind) != nullptr
or TheCall->getMetadata(StoreMDKind) != nullptr) {
TaintLog << "Decorated in a previous run" << DoLog;
break;
}
}
// 3(a) If the next `Use` to explore is a `CallInst` the taint is
// propagated interprocedurally to the callee, through the arguments
// (propagation from caller to callee)
Function *Callee = getCallee(TheCall);
// Indirect calls, calls to functions without body, and calls to
// Intrinsic::memcpy with non-constant size are considered illegal,
// because we cannot know how they will affect the CPU State
if (Callee == nullptr) {
TaintLog << "Illegal -- indirect call" << DoLog;
Results.IllegalCalls.insert(TheCall);
break;
}
if (Callee->getIntrinsicID() == Intrinsic::memcpy) {
unsigned OpNo = TheUse->getOperandNo();
revng_assert(OpNo == 0 or OpNo == 1);
if (isa<ConstantInt>(TheCall->getArgOperand(2))) {
if (OpNo == 0) {
if (TaintLog.isEnabled()) {
TaintLog << "TAINT: " << TheUser << DoLog;
TaintLog << dumpToString(TheUser) << DoLog;
}
Results.TaintedStores.insert(TheUser);
}
if (OpNo == 1) {
if (TaintLog.isEnabled()) {
TaintLog << "TAINT: " << TheUser << DoLog;
TaintLog << dumpToString(TheUser) << DoLog;
}
Results.TaintedLoads.insert(TheUser);
}
} else {
TaintLog << "Illegal -- unknown size memcpy" << DoLog;
Results.IllegalCalls.insert(TheCall);
}
break;
} else if (Callee->empty()) {
TaintLog << "Illegal -- no body" << DoLog;
Results.IllegalCalls.insert(TheCall);
break;
}
revng_assert(ReachableFunctions.contains(Callee));
// Select the correct formal argument associated with this use
const Argument *FormalArgument = nullptr;
unsigned ArgNo = 0;
for (const Argument &Arg : Callee->args()) {
ArgNo = Arg.getArgNo();
if (TheUse->getOperandNo() == ArgNo) {
FormalArgument = &Arg;
break;
}
}
TaintLog << "Found Argument" << DoLog;
revng_assert(FormalArgument != nullptr);
// Taint the Argument, and if this is the first time we taint it we
// also push on the ToTaintWorkList its first use that is not tainted.
if (TaintLog.isEnabled()) {
TaintLog << "Argument: " << FormalArgument << DoLog;
TaintLog << dumpToString(FormalArgument) << DoLog;
}
bool JustTainted = Results.TaintedValues.insert(FormalArgument).second;
if (JustTainted) {
TaintLog << "Just Tainted" << DoLog;
for (const Use &U : FormalArgument->uses()) {
if (TaintLog.isEnabled()) {
TaintLog << "User: " << U.getUser() << DoLog;
TaintLog << dumpToString(U.getUser()) << DoLog;
}
if (!Results.TaintedValues.contains(U.getUser())) {
TaintLog << "PUSH" << DoLog;
ToTaintWorkList.push(&U);
TaintLog.indent();
// We also push the call to the CallSites stack, because if we put
// the uses of the argument on the ToTaintWorkList we are actually
// starting to perform the analysis inside the callee.
CallSiteInfos.push(CallSiteInfo(TheCall, FormalArgument, ArgNo));
break;
}
}
} else if (FunctionArgTaintsReturn.contains({ Callee,
FormalArgument })) {
// It means that a previous exploration of the graph has reached this
// argument, and propagated a taint until a return value. This means
// that this we must taint the call and start exploring its unexplored
// users if any.
bool JustTainted = Results.TaintedValues.insert(TheUser).second;
if (TaintLog.isEnabled()) {
TaintLog << "TAINT: " << TheUser << DoLog;
TaintLog << dumpToString(TheUser) << DoLog;
}
if (JustTainted) {
TaintLog << "Just Tainted" << DoLog;
for (const Use &U : TheUser->uses()) {
TaintLog << "User: " << U.getUser() << DoLog;
if (!Results.TaintedValues.contains(U.getUser())) {
TaintLog << "PUSH" << DoLog;
ToTaintWorkList.push(&U);
TaintLog.indent();
break;
}
}
}
}
} break;
case Instruction::Ret: {
// 3(b) If the next `Use` to explore is a `RetInst` the taint is
// propagated interprocedurally to the Function.
// (propagation from the callee to all call sites)
TaintLog << "RET" << DoLog;
revng_assert(not CallSiteInfos.empty());
// Taint the return instruction, then, if this is the first time that we
// taint also the call site, so that it's marked for propagation of the
// taint analysis to its uses.
if (TaintLog.isEnabled()) {
TaintLog << "TAINT: " << TheUser << DoLog;
TaintLog << dumpToString(TheUser) << DoLog;
}
bool JustTainted = Results.TaintedValues.insert(TheUser).second;
if (JustTainted) {
const CallSiteInfo &CSInfo = CallSiteInfos.top();
Results.TaintedValues.insert(CSInfo.CallSite);
const Function *Callee = getCallee(CSInfo.CallSite);
FunctionArgTaintsReturn.insert({ Callee, CSInfo.Arg });
if (TaintLog.isEnabled()) {
TaintLog << "TAINT: " << CSInfo.CallSite << DoLog;
TaintLog << dumpToString(CallSiteInfos.top().CallSite) << DoLog;
llvm::StringRef Name = getCallee(CSInfo.CallSite)->getName();
TaintLog << "pair: < " << Name << ", " << CSInfo.ArgNo << " > "
<< DoLog;
}
}
} break;
case Instruction::Switch:
case Instruction::ICmp:
case Instruction::And:
case Instruction::Or:
break;
default:
revng_abort();
}
// If we pushed something new on the ToTaintWorkList we want to keep
// exploring its uses until we reach a leaf.
if (Size < ToTaintWorkList.size())
continue;
TaintLog << "not grown" << DoLog;
// 4. If we didn't push anything on the WorkList we can start exploring
// the other `Use`s of the item that is currently on top of the WorkList
if (Size == ToTaintWorkList.size()) {
Use *NextUse = TheUse->getNext();
if (NextUse != nullptr) {
TaintLog << "advance" << DoLog;
ToTaintWorkList.top() = NextUse;
continue;
}
}
TaintLog << "Done" << DoLog;
// 5. If we didn't push anything on the WorkList we can start popping
// `Use`s from the WorkList, until we reach a `Value` that still has
// unexplored `Use`s
//
// If we reach this point we have finished to explore all the uses of the
// item that is currently on top of the ToTaintWorkList stack.
// We want to pop it and to handle Arguments in a special way.
const Use *UnexploredUse = nullptr;
while (not ToTaintWorkList.empty() and UnexploredUse == nullptr) {
const Use *PoppedTopUse = ToTaintWorkList.top();
if (TaintLog.isEnabled()) {
TaintLog << "POP : " << PoppedTopUse->get() << DoLog;
TaintLog << dumpToString(PoppedTopUse->get()) << DoLog;
}
if (TaintLog.isEnabled()) {
TaintLog << "PoppedUser : " << PoppedTopUse->getUser() << DoLog;
TaintLog << dumpToString(PoppedTopUse->getUser()) << DoLog;
}
ToTaintWorkList.pop();
TaintLog.unindent();
Argument *Arg = dyn_cast<Argument>(PoppedTopUse->get());
bool PoppedHasAllExploredSources = PoppedTopUse->getNext() == nullptr;
if (Arg and PoppedHasAllExploredSources) {
// 5(a) If we're popping an argument of a function this means that we
// finished analyzing the uses of that argument. We have to make sure
// that, if the taint reached the return instructions in the function,
// the taint is propagated to the call sites.
TaintLog << "Finish Argument" << DoLog;
const CallSiteInfo &CSInfo = CallSiteInfos.top();
revng_assert(CSInfo.Arg == Arg);
unsigned ArgNo = Arg->getArgNo();
revng_assert(CSInfo.ArgNo == ArgNo);
const User *ArgUser = ToTaintWorkList.top()->getUser();
const auto *CallSite = cast<const CallInst>(ArgUser);
const Function *Callee = getCallee(CallSite);
if (TaintLog.isEnabled()) {
TaintLog << "CallSite: " << CallSite << DoLog;
TaintLog << dumpToString(CallSite) << DoLog;
}
// If the CallSite was tainted it means that the taint analysis
// reached at least one of the return values of the callee.
// Hence, the taint can propagate to the uses of the call.
// The same holds if we already know that the pair (Callee, ArgNo)
// taints the return.
if (Results.TaintedValues.contains(CallSite)
or FunctionArgTaintsReturn.contains({ Callee, Arg })) {
if (CallSite->getNumUses() != 0) {
UnexploredUse = &*CallSite->use_begin();
}
}
// If PoppedTopUse is an Use of an Argument the next available Use on
// the stack must be an argument of a CallInst. This CallInst was the
// call from where we started analyzing the uses of the function
// Argument for which we just popped the PoppedTopUse.
CallSiteInfos.pop();
} else {
TaintLog << "NOT Finished or NOT Argument" << DoLog;
UnexploredUse = PoppedTopUse->getNext();
}
}
// 6. After popping the top of the WorkList in 5., if the new top of the
// WorkList still has unexplored uses start to explore them.
// If we have a new UnexploredUse we push it and we continue
// because that's the new use that must be analyzed.
if (UnexploredUse != nullptr) {
TaintLog << "PUSH: " << UnexploredUse->get() << DoLog;
TaintLog << "User: " << UnexploredUse->getUser() << DoLog;
ToTaintWorkList.push(UnexploredUse);
TaintLog.indent();
}
}
}
if (not Lazy) {
QuickMetadata QMD(M->getContext());
for (CallInst *Call : Results.IllegalCalls) {
CallInst *Abort = CallInst::Create(M->getFunction("abort"), {}, Call);
auto IllegalCallsMDKind = M->getContext().getMDKindID("revng.csaa."
"illegal.calls");
Abort->setMetadata(IllegalCallsMDKind, QMD.tuple((uint32_t) 0));
}
}
return Results;
}
class WorkItem {
public:
using size_type = SmallVector<const Use *, 3>::size_type;
using iterator = SmallVector<const Use *, 3>::iterator;
using const_iterator = SmallVector<const Use *, 3>::const_iterator;
private:
// The value whose sources we're analyzing
Value *CurrentValue;
// Sources are kind of the opposite of `Use`s. Every pointer in this vector
// points to a `Use` whose `User` is the `Value` pointed by the `CurrentValue`
// member of this `WorkItem`.
SmallVector<const Use *, 3> Sources;
// The index of the Source that is currently considered for the analysis
size_type SourceIndex;
public:
WorkItem() : CurrentValue(nullptr), Sources(), SourceIndex(0) {}
explicit WorkItem(Instruction *I) :
CurrentValue(I), Sources(), SourceIndex(0) {
if (not isa<StoreInst>(I)) {
for (const Use &OpUse : I->operands()) {
Sources.push_back(&OpUse);
}
} else {
const auto PtrOpNum = StoreInst::getPointerOperandIndex();
Sources.push_back(&I->getOperandUse(PtrOpNum));
}
revng_assert(not Sources.empty());
}
explicit WorkItem(Argument *A,
const ConstFunctionPtrSet &ReachableFunctions,
const bool IsLazy,
const unsigned LoadMDKind,
const unsigned StoreMDKind) :
CurrentValue(A), Sources(), SourceIndex(0) {
const Function *F = A->getParent();
revng_assert(not F->empty());
revng_log(CSVAccessLog, "Function: " << F);
const unsigned ArgNo = A->getArgNo();
revng_log(CSVAccessLog, "ArgNo: " << ArgNo);
for (const Use &FUse : F->uses()) {
const User *FUser = FUse.getUser();
revng_log(CSVAccessLog, "FUser: " << FUser);
if (const auto *FCall = dyn_cast<const CallInst>(FUser)) {
revng_log(CSVAccessLog, "Is a Call");
const Function *Caller = FCall->getFunction();
revng_log(CSVAccessLog, "Caller: " << Caller);
// If this call has already been decorated with LoadMDKind or
// StoreMDKind metadata it means that it has already been processed by
// a previous run of CPUStateAccessAnalysis.
// If we're running in lazy mode, we can skip calls that have already
// been decorated.
if (IsLazy) {
if (FCall->getMetadata(LoadMDKind) != nullptr
or FCall->getMetadata(StoreMDKind) != nullptr) {
revng_log(CSVAccessLog, "Already marked");
continue;
}
}
if (ReachableFunctions.contains(Caller)) {
revng_log(CSVAccessLog,
"Is Reachable CallInst:" << FCall << " : "
<< dumpToString(FCall));
const Use &ActualArgUse = FCall->getArgOperandUse(ArgNo);
revng_log(CSVAccessLog,
"ActualUse:" << ActualArgUse.getUser() << " : "
<< dumpToString(ActualArgUse.getUser()));
Sources.push_back(&ActualArgUse);
} else {
revng_log(CSVAccessLog, "NOT Reachable");
}
} else if (const auto *CExpr = dyn_cast<const ConstantExpr>(FUser)) {
revng_log(CSVAccessLog, "Bitcast");
const auto OpCode = CExpr->getOpcode();
revng_assert(OpCode == Instruction::BitCast);
for (const User *RealCall : CExpr->users()) {
revng_log(CSVAccessLog,
"RealCall: " << RealCall << " : "
<< dumpToString(RealCall));
const auto *FCall = dyn_cast<const CallInst>(RealCall);
revng_log(CSVAccessLog,
"CallInst: " << FCall << " : " << dumpToString(FCall));
// If this call has already been decorated with LoadMDKind or
// StoreMDKind metadata it means that it has already been processed by
// a previous run of CPUStateAccessAnalysis.
// If we're running in lazy mode, we can skip calls that have already
// been decorated.
if (IsLazy) {
if (FCall->getMetadata(LoadMDKind) != nullptr
or FCall->getMetadata(StoreMDKind) != nullptr) {
revng_log(CSVAccessLog, "Already marked");
continue;
}
}
if (FCall) {
const Function *Caller = FCall->getFunction();
revng_log(CSVAccessLog, "Caller: " << Caller);
if (ReachableFunctions.contains(Caller)) {
const Use &ActualArgUse = FCall->getArgOperandUse(ArgNo);
revng_log(CSVAccessLog,
"ActualUse:" << ActualArgUse.getUser() << " : "
<< dumpToString(ActualArgUse.getUser()));
Sources.push_back(&ActualArgUse);
}
}
}
}
}
// This might be too strict, because the arguments of the root function
// don't have any sources. However, we assume that we never reach them.
revng_assert(not Sources.empty());
}
explicit WorkItem(CallInst *C,
const bool IsLoad,
const bool IsLazy,
const unsigned LoadMDKind,
const unsigned StoreMDKind) :
CurrentValue(C), Sources(), SourceIndex(0) {
revng_assert(not IsLazy
or (C->getMetadata(LoadMDKind) == nullptr
and C->getMetadata(StoreMDKind) == nullptr));
const Function *F = getCallee(C);
revng_assert(F != nullptr); // Assume no indirect calls
if (F->getIntrinsicID() == Intrinsic::memcpy) {
const Use &AddrOp = C->getOperandUse(IsLoad ? 1 : 0);
Sources.push_back(&AddrOp);
const Use &SizeOp = C->getOperandUse(2);
Sources.push_back(&SizeOp);
} else {
for (const BasicBlock &BB : *F) {
const Instruction *I = BB.getTerminator();
if (I and isa<ReturnInst>(I) and I->getNumOperands() != 0) {
revng_assert(I->getNumOperands() == 1);
const Use &RetValUse = I->getOperandUse(0);
Sources.push_back(&RetValUse);
}
}
}
revng_assert(not Sources.empty());
}
public:
friend inline void writeToLog(Logger<true> &L, const WorkItem &I, int) {
L << "Value: " << I.val() << " : " << dumpToString(I.val()) << DoLog;
L << "Sources = {" << DoLog;
L.indent();
for (const Use *U : I.sources())
L << U->get() << " : " << dumpToString(U->get()) << DoLog;
L << "}" << DoLog;
L << "Curr Src Id: " << I.SourceIndex;
L.unindent();
}
public:
Value *val() const { return CurrentValue; };
const Use *currentSourceUse() const {
if (SourceIndex < Sources.size())
return Sources[SourceIndex];
return nullptr;
}
Value *currentSourceValue() const {
const Use *CurrUse = currentSourceUse();
return CurrUse ? CurrUse->get() : nullptr;
}
const Use *nextSourceUse() const {
const auto Size = Sources.size();
if (SourceIndex < Size and (SourceIndex + 1) < Size)
return Sources[SourceIndex + 1];
return nullptr;
}
Value *nextSourceValue() const {
const Use *CurrUse = nextSourceUse();
return CurrUse ? CurrUse->get() : nullptr;
}
size_type getSourceIndex() const { return SourceIndex; }
void setSourceIndex(size_type I) {
revng_assert(I < Sources.size());
SourceIndex = I;
}
size_type getNumSources() const { return Sources.size(); }
llvm::iterator_range<const_iterator> sources() const {
return { Sources.begin(), Sources.end() };
}
};
/// Gets a valid pointer to `CallInst` if the current source of `Item` is a call
/// from `Root`
///
/// This function returns `nullptr` if the current source of `Item` is not a
/// call from `Root`
static CallInst *getCurSourceRootCall(const WorkItem &Item,
const Function *Root) {
revng_log(CSVAccessLog, "getCurSourceRootCall");
CallInst *RootCall = nullptr;
if (isa<Argument>(Item.val())) {
revng_log(CSVAccessLog, "isa<Argument>");
User *ActualArgUser = Item.currentSourceUse()->getUser();
auto *Call = cast<CallInst>(ActualArgUser);
revng_log(CSVAccessLog, "argument: " << dumpToString(Item.val()));
revng_log(CSVAccessLog, "call: " << dumpToString(Call));
Function *F = Call->getFunction();
revng_log(CSVAccessLog, "parent: " << F->getName());
if (F == Root)
RootCall = Call;
}
revng_log(CSVAccessLog, RootCall);
return RootCall;
}
/// Gets a valid pointer to `CallInst` if the next source of `Item` is a call
/// from `Root`
///
/// This function return `nullptr` if the next source of `Item` is not a call
/// from `Root`
static CallInst *getNextSourceRootCall(const WorkItem &Item,
const Function *Root) {
revng_log(CSVAccessLog, "getNextSourceRootCall");
CallInst *RootCall = nullptr;
if (isa<Argument>(Item.val())) {
revng_log(CSVAccessLog, "isa<Argument>");
const Use *NextSrcUse = Item.nextSourceUse();
if (NextSrcUse != nullptr) {
User *ActualArgUser = NextSrcUse->getUser();
auto *Call = cast<CallInst>(ActualArgUser);
revng_log(CSVAccessLog, "argument: " << dumpToString(Item.val()));
revng_log(CSVAccessLog, "call: " << dumpToString(Call));
Function *F = Call->getFunction();
revng_log(CSVAccessLog, "parent: " << F->getName());
if (F == Root)
RootCall = Call;
}
}
revng_log(CSVAccessLog, RootCall);
return RootCall;
}
/// Gets the `Shift`-th bit of `Input`
static int getBit(uint64_t Input, int Shift) {
return (Input >> Shift) & 1;
};
using CallSiteOffsetMap = std::map<CallInst *, CSVOffsets>;
using ValueCallSiteOffsetMap = std::map<Value *, CallSiteOffsetMap>;
using OptCSVOffsets = std::optional<CSVOffsets>;
/// This class is used to fold constant offsets on different instructions
template<class T>
class CRTPOffsetFolder {
protected:
using offset_iterator = std::set<int64_t>::const_iterator;
using offset_iterator_range = llvm::iterator_range<offset_iterator>;
using OffsetPair = std::pair<const CSVOffsets *, const CSVOffsets *>;
protected:
// These should be constant but ConstantInt::get() does not have
// const-qualifier on the first argument:
// static ConstantInt *get(IntegerType *Ty, uint64_t V, bool isSigned=false)
// However, it does not really change Ty, because it only call const
// methods on it, so it should be safe.
IntegerType *Int64Ty;
IntegerType *Int32Ty;
const DataLayout &DL;
public:
CRTPOffsetFolder(const Module &M) :
Int64Ty(IntegerType::getInt64Ty(M.getContext())),
Int32Ty(IntegerType::getInt32Ty(M.getContext())),
DL(M.getDataLayout()) {}
static void insertOrCombine(Value *V,
CallInst *C,
CSVOffsets &&O,
ValueCallSiteOffsetMap &OffsetMap) {
revng_log(CSVAccessLog, "MAP: " << V);
bool Inserted;
CallSiteOffsetMap::iterator It;
std::tie(It, Inserted) = OffsetMap[V].insert(std::make_pair(C, O));
if (not Inserted)
It->second.combine(O);
}
public:
/// This method folds the offsets on the sources to Item
///
/// \param Item is the `WorkItem` whose sources must be folded
/// \param [in, out] is the Map used to retrieve the values of the offsets of
/// the sources of `Item`, and also to store the result of
/// the folded offsets for `Item`.
void fold(const WorkItem &Item, ValueCallSiteOffsetMap &OffsetMap) {
WorkItem::size_type NumSrcs = Item.getNumSources();
revng_assert(NumSrcs);
SmallVector<Constant *, 4> Operands(NumSrcs, nullptr);
// Collect Call Sites across all the sources of this User
CallPtrSet CallSites;
SmallVector<const CallSiteOffsetMap *, 4> SrcCallSiteOffsetsPtrs;
SmallVector<const CSVOffsets *, 4> NonRootOffsetsPtrs;
SrcCallSiteOffsetsPtrs.reserve(NumSrcs);
NonRootOffsetsPtrs.reserve(NumSrcs);
for (const Use *U : Item.sources()) {
const CallSiteOffsetMap &CallSiteOffsets = OffsetMap.at(U->get());
revng_assert(not CallSiteOffsets.empty());
const CSVOffsets *NonRootOffsets = nullptr;
for (const auto &CSO : CallSiteOffsets) {
CallInst *TheCall = CSO.first;
CallSites.insert(TheCall);
if (TheCall == nullptr) {
NonRootOffsets = &CSO.second;
}
}
// The order of iteration on SrcCallSiteOffsetsPtrs is the same
// as the order of iteration on Item.sources()
SrcCallSiteOffsetsPtrs.push_back(&CallSiteOffsets);
// The order of iteration on NonRootOffsets is the same as the order
// of iteration on Item.sources()
NonRootOffsetsPtrs.push_back(NonRootOffsets);
}
revng_assert(NumSrcs == SrcCallSiteOffsetsPtrs.size());
revng_assert(NumSrcs == NonRootOffsetsPtrs.size());
if (CSVAccessLog.isEnabled())
for (const CallInst *C : CallSites)
CSVAccessLog << "C: " << C << " : " << dumpToString(C) << DoLog;
// Check that each source has all the callsites or nullptr
for (const auto &CSOffsets : SrcCallSiteOffsetsPtrs) {
bool FoundNullptr = false;
if (CSOffsets->contains(nullptr))
FoundNullptr = true;
bool FoundAllCalls = true;
for (CallInst *C : CallSites) {
if (C != nullptr and not CSOffsets->contains(C)) {
FoundAllCalls = false;
break;
}
}
revng_assert(FoundNullptr or FoundAllCalls);
}
for (CallInst *C : CallSites) {
SmallVector<OffsetPair, 4> SrcOffsets(NumSrcs,
OffsetPair(nullptr, nullptr));
bool EmptyPair = false;
for (WorkItem::size_type SI = 0; SI < NumSrcs; ++SI) {
const CSVOffsets *NonRootOffset = NonRootOffsetsPtrs[SI];
if (C != nullptr)
SrcOffsets[SI].second = NonRootOffset;
const auto CallSiteOffsets = SrcCallSiteOffsetsPtrs[SI];
auto OffsetsEnd = CallSiteOffsets->end();
auto OffsetsIt = CallSiteOffsets->find(C);
if (OffsetsIt != OffsetsEnd)
SrcOffsets[SI].first = &OffsetsIt->second;
if (SrcOffsets[SI].first == nullptr
and SrcOffsets[SI].second == nullptr) {
// This means that one the pairs is empty and we can drop entirely
// this call. This happens when C == nullptr and one of the sources
// has no nullptr call site
EmptyPair = true;
}
}
if (EmptyPair)
continue;
revng_log(CSVAccessLog, "start");
revng_assert(NumSrcs < (8ULL * sizeof(uint64_t)));
uint64_t Combinations = 1ULL << NumSrcs;
Value *V = Item.val();
Instruction *I = cast<Instruction>(V);
for (uint64_t Index = 0; Index < Combinations; ++Index) {
revng_log(CSVAccessLog, "Index: " << Index);
SmallVector<const CSVOffsets *, 4> OffsetTuple;
OffsetTuple.reserve(NumSrcs);
// Build the tuple of offset sets that we want to use to compute the
// transfer function. If the analyzed call is nullptr we can skip
// some stuff and keep the computation smaller.
revng_log(CSVAccessLog, "callsite: " << C << " : " << dumpToString(C));
if (C != nullptr) {
for (WorkItem::size_type SI = 0; SI < NumSrcs; ++SI) {
int Bit = getBit(Index, SI);
const CSVOffsets *O0 = SrcOffsets[SI].first;
const CSVOffsets *O1 = SrcOffsets[SI].second;
const CSVOffsets *O = Bit ? O1 : O0;
if (O == nullptr)
break;
revng_log(CSVAccessLog, "nonnull");
OffsetTuple.push_back(O);
}
} else {
for (WorkItem::size_type SI = 0; SI < NumSrcs; ++SI) {
const CSVOffsets *O = NonRootOffsetsPtrs[SI];
if (O == nullptr)
break;
revng_log(CSVAccessLog, "nonnull");
OffsetTuple.push_back(O);
}
}
revng_log(CSVAccessLog,
"NumSrcs:" << NumSrcs
<< " -- Tuple Size:" << OffsetTuple.size());
if (OffsetTuple.size() != NumSrcs)
continue;
bool Valid;
CSVOffsets::Kind ResKind;
SmallVector<optional<CSVOffsets>, 4> UpdatedOffsetTuple(NumSrcs);
revng_assert(not UpdatedOffsetTuple[0].has_value());
std::tie(Valid,
ResKind) = T::checkOffsetTupleIsValid(OffsetTuple,
I,
UpdatedOffsetTuple);
revng_assert(UpdatedOffsetTuple.size() == OffsetTuple.size());
if (not Valid) {
insertOrCombine(V, C, CSVOffsets(ResKind), OffsetMap);
continue;
}
revng_log(CSVAccessLog, "valid tuple");
SmallVector<offset_iterator_range, 4> OffsetsRanges;
SmallVector<offset_iterator, 4> OffsetsIt;
OffsetsRanges.reserve(NumSrcs);
OffsetsIt.reserve(NumSrcs);
WorkItem::size_type CartesianSize = 1;
for (WorkItem::size_type SI = 0; SI < NumSrcs; ++SI) {
OptCSVOffsets &UpdatedOffsets = UpdatedOffsetTuple[SI];
bool WasUpdated = UpdatedOffsets.has_value();
const CSVOffsets *Tuple = WasUpdated ? &*UpdatedOffsets :
OffsetTuple[SI];
OffsetsRanges.push_back(make_range(Tuple->begin(), Tuple->end()));
OffsetsIt.push_back(Tuple->begin());
const WorkItem::size_type OffsetSize = Tuple->size();
revng_assert(OffsetSize);
revng_assert(CartesianSize <= CartesianSize * OffsetSize);
CartesianSize *= OffsetSize;
}
do {
CSVOffsets ResOffset = foldOffsets(ResKind, NumSrcs, I, OffsetsIt);
insertOrCombine(V, C, std::move(ResOffset), OffsetMap);
// Advance the iterators
{
WorkItem::size_type SI = 0;
bool Wrapped = false;
do {
revng_log(CSVAccessLog, "SI: " << SI);
if (std::next(OffsetsIt[SI]) == OffsetsRanges[SI].end()) {
OffsetsIt[SI] = OffsetsRanges[SI].begin();
Wrapped = true;
revng_log(CSVAccessLog, "WRAP");
} else {
revng_log(CSVAccessLog, "NO-WRAP");
std::advance(OffsetsIt[SI], 1);
Wrapped = false;
}
} while (Wrapped and ++SI < NumSrcs);
revng_log(CSVAccessLog, "incremented");
}
} while (--CartesianSize);
}
}
}
private:
CSVOffsets foldOffsets(CSVOffsets::Kind ResKind,
WorkItem::size_type NumSrcs,
Instruction *I,
const SmallVector<offset_iterator, 4> &OffsetsIt) {
return static_cast<T *>(this)->foldOffsets(ResKind, NumSrcs, I, OffsetsIt);
}
};
/// Specialization of CRTPOffsetFolder for sums and subtractions
class AddSubOffsetFolder : public CRTPOffsetFolder<AddSubOffsetFolder> {
public:
AddSubOffsetFolder(const Module &M) :
CRTPOffsetFolder<AddSubOffsetFolder>(M) {}
public:
friend class CRTPOffsetFolder<AddSubOffsetFolder>;
private:
static std::pair<bool, CSVOffsets::Kind>
checkOffsetTupleIsValid(const SmallVector<const CSVOffsets *, 4> &OffsetTuple,
const Instruction *I,
SmallVector<OptCSVOffsets, 4> &) {
revng_assert(OffsetTuple.size() == 2);
auto OpCode = I->getOpcode();
revng_assert(OpCode == Instruction::Add or OpCode == Instruction::Sub);
const auto O0 = OffsetTuple[0], O1 = OffsetTuple[1];
if (OpCode == Instruction::Add) {
// Cannot add pointers
revng_assert(not(O0->isPtr() and O1->isPtr()));
} else {
// Cannot subtract a pointer from something else
revng_assert(not O1->isPtr());
}
if (O0->isUnknown() or O1->isUnknown()) {
if (O0->isOnlyInPtr() or O1->isOnlyInPtr())
return { false, CSVOffsets::Kind::UnknownInPtr };
if (O0->isInOutPtr() or O1->isInOutPtr())
return { false, CSVOffsets::Kind::OutAndUnknownInPtr };
return { false, CSVOffsets::Kind::Unknown };
}
{
bool Num0 = O0->isNumeric();
if (Num0 or O1->isNumeric()) {
CSVOffsets::Kind ResKind = Num0 ? O1->getKind() : O0->getKind();
if (O0->isUnknownInPtr() or O1->isUnknownInPtr())
return { false, ResKind };
else
return { true, ResKind };
}
}
revng_abort();
}
CSVOffsets foldOffsets(CSVOffsets::Kind ResultKind,
WorkItem::size_type NumSrcs,
Instruction *I,
const SmallVector<offset_iterator, 4> &OffsetsIt) {
auto OpCode = I->getOpcode();
revng_assert(OpCode == Instruction::Add or OpCode == Instruction::Sub);
SmallVector<Constant *, 4> Operands(NumSrcs, nullptr);
// Setup operands
for (WorkItem::size_type SI = 0; SI < NumSrcs; ++SI) {
const int64_t O = *OffsetsIt[SI];
Operands[SI] = ConstantInt::get(Int64Ty, APInt(64, O, true));
}
// Constant fold the operation with the selected operands
ArrayRef<Constant *> TmpOp(Operands);
Constant *Res = ConstantFoldInstOperands(I, TmpOp, DL);
ConstantInt *R = cast<ConstantInt>(Res);
const int64_t ResO = R->getSExtValue();
return CSVOffsets(ResultKind, ResO);
}
};
/// Specialization of CRTPOffsetFolder for GEPs
class GEPOffsetFolder : public CRTPOffsetFolder<GEPOffsetFolder> {
public:
GEPOffsetFolder(const Module &M) : CRTPOffsetFolder<GEPOffsetFolder>(M) {}
public:
friend class CRTPOffsetFolder<GEPOffsetFolder>;
private:
static std::pair<bool, CSVOffsets::Kind>
checkOffsetTupleIsValid(const SmallVector<const CSVOffsets *, 4> &OffsetTuple,
const Instruction *I,
SmallVector<OptCSVOffsets, 4> &UpdatedOffsetTuple) {
auto OpCode = I->getOpcode();
revng_assert(OpCode == Instruction::GetElementPtr);
size_t NOperands = OffsetTuple.size();
revng_assert(NOperands > 1);
CSVOffsets::Kind GEPOp0Kind = OffsetTuple[0]->getKind();
if (CSVOffsets::isUnknownInPtr(GEPOp0Kind)
or CSVOffsets::isUnknown(GEPOp0Kind))
return { false, GEPOp0Kind };
auto *GEP = cast<GetElementPtrInst>(I);
Type *PointeeTy = GEP->getSourceElementType();
if (GEP->hasIndices() and PointeeTy->isArrayTy()) {
auto FirstIdxConst = dyn_cast<ConstantInt>(*GEP->idx_begin());
bool FirstIdxPropagatedConst = OffsetTuple[1]->size() == 1;
revng_assert(not(FirstIdxConst != nullptr) or FirstIdxPropagatedConst);
if (FirstIdxPropagatedConst) {
bool FirstIdxZero = FirstIdxConst->isZero();
bool FirstIdxPropagatedZero = *OffsetTuple[1]->begin() == 0;
revng_assert(not FirstIdxZero or FirstIdxPropagatedZero);
if (FirstIdxPropagatedZero) {
SmallVector<uint64_t, 4> ConstIdxList = { 0 };
auto IdxIt = GEP->idx_begin();
auto IdxEnd = GEP->idx_end();
int IdxOpNum = 1;
std::set<int64_t> LastTypeOffsets = { 0 };
for (; IdxIt != IdxEnd; ++IdxIt, ++IdxOpNum) {
const CSVOffsets *IdxCSVOffset = OffsetTuple[IdxOpNum];
revng_assert(not IdxCSVOffset->isPtr());
Type *ElementTy = GEP->getIndexedType(PointeeTy, ConstIdxList);
if (ElementTy->isAggregateType()) {
if (ElementTy->isArrayTy()) {
if (IdxCSVOffset->isUnknown()) {
CSVOffsets U(CSVOffsets::Kind::Numeric, LastTypeOffsets);
UpdatedOffsetTuple[IdxOpNum] = std::move(U);
} else {
// If it's not Unknown we can leave it like it is.
}
auto *ArrayTy = cast<ArrayType>(ElementTy);
uint64_t ArrayNumElem = ArrayTy->getNumElements();
revng_assert(ArrayNumElem);
LastTypeOffsets.clear();
for (uint64_t O = 0; O < ArrayNumElem; ++O)
LastTypeOffsets.insert(O);
ConstIdxList.push_back(0);
} else if (ElementTy->isStructTy()) {
if (IdxCSVOffset->isUnknown()) {
if (IdxIt + 1 != IdxEnd) {
// I cannot fold structs with unknown index.
// Early exit.
return { false, CSVOffsets::makeUnknown(GEPOp0Kind) };
} else {
revng_assert(not LastTypeOffsets.empty());
CSVOffsets U(CSVOffsets::Kind::Numeric, LastTypeOffsets);
UpdatedOffsetTuple[IdxOpNum] = std::move(U);
break;
}
} else {
// If it's not Unknown we can leave it like it is.
revng_assert(not IdxCSVOffset->empty());
ConstIdxList.push_back(*IdxCSVOffset->begin());
revng_assert(IdxCSVOffset->size() != 0);
LastTypeOffsets.clear();
LastTypeOffsets.insert(IdxCSVOffset->begin(),
IdxCSVOffset->end());
}
} else {
revng_abort();
}
} else {
// I'm done.
revng_assert(IdxIt + 1 == IdxEnd);
if (IdxCSVOffset->isUnknown()) {
CSVOffsets U(CSVOffsets::Kind::Numeric, LastTypeOffsets);
UpdatedOffsetTuple[IdxOpNum] = std::move(U);
} else {
// If it's not Unknown we can leave it like it is.
}
}
}
return { true, GEPOp0Kind };
} else {
// For now we don't handle cases when the first index of the GEP is
// not zero, so in those case we fall back outside the if and we fold
// them as usual.
}
} else {
// For now we don't handle cases when the first index of the GEP is
// not constant, so in those case we fall back outside the if and we
// fold them as usual.
}
} else {
// For now we don't handle cases when the GEP does not index an array, so
// in those case we fall back outside the if and we fold them as usual.
}
for (size_t O = 1; O < NOperands; O++) {
revng_assert(not OffsetTuple[O]->isPtr());
if (OffsetTuple[O]->isUnknown())
return { false, CSVOffsets::makeUnknown(GEPOp0Kind) };
}
return { true, GEPOp0Kind };
}
CSVOffsets foldOffsets(CSVOffsets::Kind ResultKind,
WorkItem::size_type NumSrcs,
Instruction *I,
const SmallVector<offset_iterator, 4> &OffsetsIt) {
const auto *GEP = cast<const GetElementPtrInst>(I);
const auto PtrOpTy = GEP->getPointerOperand()->getType();
SmallVector<Constant *, 4> Operands(NumSrcs, nullptr);
// Setup operands
int64_t PtrOp = *OffsetsIt[0];
Operands[0] = Constant::getIntegerValue(PtrOpTy, APInt(64, PtrOp, true));
for (WorkItem::size_type SI = 1; SI < NumSrcs; ++SI) {
const int64_t O = *OffsetsIt[SI];
Operands[SI] = ConstantInt::get(Int32Ty, APInt(32, O, true));
}
// Constant fold the operation with the selected operands
ArrayRef<Constant *> TmpOp(Operands);
Constant *Res = ConstantFoldInstOperands(I, TmpOp, DL);
ConstantInt *R = getConstValue(Res, DL);
const int64_t ResO = getSExtValue(R, DL);
return CSVOffsets(ResultKind, ResO);
}
};
/// Specialization of CRTPOffsetFolder for non-address binary operations
class NumericOffsetFolder : public CRTPOffsetFolder<NumericOffsetFolder> {
public:
NumericOffsetFolder(const Module &M) :
CRTPOffsetFolder<NumericOffsetFolder>(M) {}
public:
friend class CRTPOffsetFolder<NumericOffsetFolder>;
private:
static std::pair<bool, CSVOffsets::Kind>
checkOffsetTupleIsValid(const SmallVector<const CSVOffsets *, 4> &OffsetTuple,
const Instruction *I,
SmallVector<OptCSVOffsets, 4> &) {
revng_assert(OffsetTuple.size() == 2);
auto OpCode = I->getOpcode();
revng_assert(OpCode == Instruction::Shl or OpCode == Instruction::AShr
or OpCode == Instruction::LShr or OpCode == Instruction::Mul
or OpCode == Instruction::URem or OpCode == Instruction::SRem
or OpCode == Instruction::SDiv or OpCode == Instruction::UDiv);
const auto O0 = OffsetTuple[0], O1 = OffsetTuple[1];
revng_assert(not O0->isPtr() and not O1->isPtr());
if (O0->isUnknown() or O1->isUnknown()) {
return std::make_pair(false, CSVOffsets::Kind::Unknown);
} else {
return std::make_pair(true, CSVOffsets::Kind::Numeric);
}
}
CSVOffsets foldOffsets(CSVOffsets::Kind ResultKind,
WorkItem::size_type NumSrcs,
Instruction *I,
const SmallVector<offset_iterator, 4> &OffsetsIt) {
auto OpCode = I->getOpcode();
revng_assert(OpCode == Instruction::Shl or OpCode == Instruction::AShr
or OpCode == Instruction::LShr or OpCode == Instruction::Mul
or OpCode == Instruction::URem or OpCode == Instruction::SRem
or OpCode == Instruction::SDiv or OpCode == Instruction::UDiv);
SmallVector<Constant *, 4> Operands(NumSrcs, nullptr);
// Setup operands
for (WorkItem::size_type SI = 0; SI < NumSrcs; ++SI) {
const int64_t O = *OffsetsIt[SI];
Operands[SI] = ConstantInt::get(Int64Ty, APInt(64, O, true));
}
// Constant fold the operation with the selected operands
ArrayRef<Constant *> TmpOp(Operands);
Constant *Res = ConstantFoldInstOperands(I, TmpOp, DL);
ConstantInt *R = cast<ConstantInt>(Res);
const int64_t ResO = R->getSExtValue();
return CSVOffsets(ResultKind, ResO);
}
};
using AccessOffsetMap = CPUStateAccessAnalysisPass::AccessOffsetMap;
class CPUStateAccessOffsetAnalysis {
private:
const bool Lazy;
const unsigned LoadMDKind;
const unsigned StoreMDKind;
const Module &M;
const Value *CPUStatePtr;
const Function *RootFunction;
const ConstFunctionPtrSet &ReachableFunctions;
const TaintResults &TaintedAccesses;
VariableManager *Variables;
AccessOffsetMap &LoadOffsets; // result, maps load or load-memcpy to offsets
AccessOffsetMap &StoreOffsets; // result, maps store or store-memcpy to
// offsets
CallSiteOffsetMap &CallSiteLoadOffsets; // result, maps call in root to load
// offsets
CallSiteOffsetMap &CallSiteStoreOffsets; // result, maps call in root to store
// offsets
// ValueCallSiteOffsets is used to keep track of the offsets associated with
// each value. The primary key is the `Value` for which we're tracking the
// offsets. The secondary key is a `CallInst` representing a call site in
// root. This call site represents the call from which the mapped offsets are
// possible. The mapped value is a `CSVOffsets`.
ValueCallSiteOffsetMap ValueCallSiteOffsets;
// The two following maps have the same structure as ValueCallSiteOffsets, but
// they are use to hold results on the specific loads and stores that access
// CSV. They are used after the computation to generate the metadata to attach
// to the root call sites and the final results of the analysis.
ValueCallSiteOffsetMap LoadCallSiteOffsets;
ValueCallSiteOffsetMap StoreCallSiteOffsets;
CallPtrSet CrossedCallSites;
using WorkListVector = std::vector<WorkItem>;
WorkListVector WorkList;
ConstValuePtrSet InExploration;
// Helper folders
AddSubOffsetFolder AddSubFolder;
NumericOffsetFolder NumericFolder;
GEPOffsetFolder GEPFolder;
const Function *CpuLoop;
public:
CPUStateAccessOffsetAnalysis(const Module &Mod,
const Value *EnvPtr,
const Function *Root,
const ConstFunctionPtrSet &Reachable,
const TaintResults &Tainted,
const bool IsLazy,
const unsigned LoadKind,
const unsigned StoreKind,
VariableManager *Vars,
AccessOffsetMap &LoadOff,
AccessOffsetMap &StoreOff,
CallSiteOffsetMap &CallSiteLoadOff,
CallSiteOffsetMap &CallSiteStoreOff) :
Lazy(IsLazy),
LoadMDKind(LoadKind),
StoreMDKind(StoreKind),
M(Mod),
CPUStatePtr(EnvPtr),
RootFunction(Root),
ReachableFunctions(Reachable),
TaintedAccesses(Tainted),
Variables(Vars),
LoadOffsets(LoadOff),
StoreOffsets(StoreOff),
CallSiteLoadOffsets(CallSiteLoadOff),
CallSiteStoreOffsets(CallSiteStoreOff),
ValueCallSiteOffsets(),
LoadCallSiteOffsets(),
StoreCallSiteOffsets(),
CrossedCallSites(),
WorkList(),
InExploration(),
AddSubFolder(M),
NumericFolder(M),
GEPFolder(M),
CpuLoop(M.getFunction("cpu_loop")) {}
public:
bool run();
private:
void cleanup() {
ValueCallSiteOffsets = {};
LoadCallSiteOffsets = {};
StoreCallSiteOffsets = {};
CrossedCallSites = {};
WorkList = {};
InExploration = {};
}
/// Analyzes the access to env performed by \p I, saving results according to
/// \p IsLoad
///
/// \param I is the `Instruction` whose accesses are analyzed
/// \param IsLoad must be true if called when analyzing loads, false if called
/// when analyzing stores. This is important because it is used to
/// update the correct ValueCallSiteOffsetMap (either
/// LoadCallSiteOffsets or StoreCallSiteOffsets) if during
/// the exploration the analysis ends because all the immediate sources
/// are already resolved.
void analyzeAccess(Instruction *I, bool IsLoad);
/// Explores the sources of `V` and pushes a `WorkItem` on `WorkList`
/// if something new is found
///
/// \param V is the `Value` whose sources are analyzed
/// \param IsLoad must be true if called when propagating loads, false if
/// called when propagating stores. This is important because it is used to
/// update the correct ValueCallSiteOffsetMap (either LoadCallSiteOffsets or
/// StoreCallSiteOffsets) if during the exploration the analysis ends because
/// all the immediate sources are already resolved.
bool exploreImmediateSources(Value *V, bool IsLoad);
/// Returns an emptyoOptional and fill W if there are unexplored sources,
/// otherwise return the offsets
///
/// \param V the `Value` whose sources must be explored.
/// \param [out] W a `WorkItem` that will be initialized with the unexplored
/// sources of `V` if any.
/// \param IsLoad true if we're exploring from a load
OptCSVOffsets
getOffsetsOrExploreSrc(Value *V, WorkItem &W, bool IsLoad) const;
void insertCallSiteOffset(Value *V, CSVOffsets &&Offset);
/// Removes the root call site associated with `Item` (if any) from
/// `CrossedCallSites`
///
/// \return `true` if it was removed, `false` otherwise
bool tryRemoveCurCrossedCallSite(const WorkItem &Item) {
if (CallInst *RootCallSite = getCurSourceRootCall(Item, RootFunction))
return CrossedCallSites.erase(RootCallSite);
return false;
}
/// Returns true if `V` is visited for the first time with the callsite
/// `NewCallSite`
///
/// \param V is the `Value` that is being visited
/// \param NewCallSite is the new call site from which we're exploring V and
/// we want to check if it's the first time we visit V with that
/// particular call site
///
/// This function returns `true` if this is the first visit, `false` otherwise
bool isNewVisitWithCallSite(Value *V, CallInst *NewCallSite) const {
if (CSVAccessLog.isEnabled()) {
if (NewCallSite != nullptr) {
llvm::StringRef NameRef = NewCallSite->getFunction()->getName();
revng_log(CSVAccessLog, "caller: " << NameRef);
} else {
revng_log(CSVAccessLog, "caller: nullptr");
}
}
// Handle constants in a special way. Constants are kind of global values
// that can be used across different functions without properly propagating
// on the call graph across call sites.
// This has two consequences.
// 1) On the one hand we don't want to track their exact call site, because
// they can propagate independently of the call sites. Hence all constants
// are collected with an 'artificial' nullptr callsite (see the else).
// 2) On the other hand, when we cross root call sites and we find that one
// of the arguments is a constant, we want to mark it every time as a new
// visit. If we don't mark it as a new visit, the root call site will not be
// crossed, hence it will not be inserted in the `CrossedCallSites`, which
// is not what we want because it would lead to errors in computing the root
// call sites that are active for a given exploration. For this reason, if V
// is a constant and (NewCallSite != nullptr) we always say it's a new
// visit, because it means we're crossing a root call site towards a
// constant argument.
if (isa<ConstantInt>(V)) {
if (NewCallSite != nullptr)
return true;
else
NewCallSite = nullptr;
}
const auto CallSiteOffsetIt = ValueCallSiteOffsets.find(V);
// If the ValueCallSiteOffsets does not contain V it's a new visit
if (CallSiteOffsetIt == ValueCallSiteOffsets.end())
return true;
// If the ValueCallSiteOffsets contains V we have already analyzed visited
// this value, but we don't know which call sites were contained in
// CrossedCallSites during the last visit.
const CallSiteOffsetMap &ACSOMap = CallSiteOffsetIt->second;
// If NewCallSite is not nullptr, we are crossing a new callsite in the root
// function, so we start looking in the ValueCallSiteOffsets for an entry
// associated to NewCallSite
if (NewCallSite) {
// If we find that ValueCallSiteOffsets still does not contain an entry
// associated to NewCallSite this visit is considered new
if (!ACSOMap.contains(NewCallSite))
return true;
}
// If CrossedCallSites is not empty, we have crossed at least one call site
// in the root function, so we need to look in CrossedCallSites if there is
// a new call site to analyze
if (not CrossedCallSites.empty()) {
for (CallInst *Call : CrossedCallSites) {
// If we find a call site in CrossedCallSites for which the
// ValueCallSiteOffsets
// still does not contain a result for this value this visit is
// considered new
if (!ACSOMap.contains(Call))
return true;
}
} else {
// If CrossedCallSites is empty, we haven't crossed any call site in the
// root function, so we look for nullptr.
if (!ACSOMap.contains(nullptr))
return true;
}
// If we reach this point the ValueCallSiteOffsets already contains an entry
// for V, and all the current CrossedCallSites have already been computed
// for that entry, so the visit is not new
return false;
}
/// If it's a new visit, insert the call `RootCall` (associated with `U`)
/// in `CrossedCallSites`
///
/// \param RootCall must be nullptr or a valid call instruction in root
/// \param U if RootCall is not `nullptr` this is a `Use` whose `User` must be
/// RootCall
/// \return `true` if it was a new visit, `false` otherwise.
///
/// If this is the first visit, `RootCall` is inserted in `CrossedCallSites`
/// and the function returns `true`.
/// If this is not the first visit or `RootCall` it returns `false`
bool checkNewVisitAndInsertCrossedCallSite(CallInst *RootCall, const Use *U) {
revng_log(CSVAccessLog, "isNewVisitWithCallSite?");
if (isNewVisitWithCallSite(U->get(), RootCall)) {
if (RootCall) {
revng_log(CSVAccessLog, "is RootCall");
bool New = CrossedCallSites.insert(RootCall).second;
revng_assert(New);
}
revng_log(CSVAccessLog, "isNewVisitWithCallSite true");
return true;
}
revng_log(CSVAccessLog, "isNewVisitWithCallSite false");
return false;
}
bool checkNewVisitAndInsertCurCrossedCallSite(const WorkItem &Item) {
CallInst *RootCallSite = getCurSourceRootCall(Item, RootFunction);
return checkNewVisitAndInsertCrossedCallSite(RootCallSite,
Item.currentSourceUse());
}
bool checkNewVisitAndInsertNextCrossedCallSite(const WorkItem &Item) {
CallInst *RootCallSite = getNextSourceRootCall(Item, RootFunction);
return checkNewVisitAndInsertCrossedCallSite(RootCallSite,
Item.nextSourceUse());
}
bool tryPush(WorkItem &&N) {
// If we're visiting the sources of an argument we are crossing a
// new call site, which might lead us into the root function.
// If it does, we want to register it in the CrossedCallSites
if (checkNewVisitAndInsertCurCrossedCallSite(N)) {
revng_log(CSVAccessLog, "Found!");
push(std::move(N));
return true;
}
revng_log(CSVAccessLog, "NOT Found!");
return false;
}
/// Selects the next source of `Item`, if possible, returning true on success.
bool selectNextSource(WorkItem &Item) {
if (Item.nextSourceUse()) {
tryRemoveCurCrossedCallSite(Item);
checkNewVisitAndInsertNextCrossedCallSite(Item);
auto NumSrcs = Item.getNumSources();
auto NextSrcId = Item.getSourceIndex() + 1;
revng_assert(NextSrcId < NumSrcs);
Item.setSourceIndex(NextSrcId);
return true;
}
return false;
}
void push(WorkItem &&Item) {
InExploration.insert(Item.val());
WorkList.push_back(Item);
CSVAccessLog.indent(2);
}
void pop() {
InExploration.erase(WorkList.back().val());
WorkList.pop_back();
CSVAccessLog.unindent(2);
}
bool isInExploration(const Value *V) const {
return InExploration.contains(V);
}
void computeOffsetsFromSources(const WorkItem &Item, bool IsLoad);
template<bool IsLoad>
void computeAggregatedOffsets();
};
using CPUSAOA = CPUStateAccessOffsetAnalysis;
void CPUSAOA::computeOffsetsFromSources(const WorkItem &Item, bool IsLoad) {
Value *ItemVal = Item.val();
if (isa<PHINode>(ItemVal) or isa<Argument>(ItemVal)
or isa<CallInst>(ItemVal)) {
// These three cases represent points of convergence of information coming
// from different origins.
//
// For `PHINode` the information comes from the different branches of the
// phi. As an example the 'then' branch of an 'if' could compute an offsets,
// whereas the 'else' branch could compute a different offset.
//
// For `Argument` the different sources of information are all the actual
// arguments of all the calls to the function that are associated to the
// formal `Argument` that we're analyzing. An example is that if the
// function `int a(int b, int c)` if called in two places, such as `f(1,2)`
// and `f(3,4)`, we have that 1 and 3 are the sources of the argument `b`.
//
// For `CallInst` we are considering the propagation of values from the
// `return` instructions inside the callee to the call site.
// For example if we have:
// ```
// int a(int b) {
// if (b) {
// int ret1 = b >> 2;
// return ret1;
// } else {
// int ret2 = b << 2;
// return ret2;
// }
// }
// ```
// and `a` is called such as:
// ```
// y = f(x);
// ...
// ```
// the sources of the `CallInst` are `ret1` and `ret2`.
revng_log(CSVAccessLog, "POP JOIN");
SmallVector<const CallSiteOffsetMap *, 10> SrcCallSiteOffsets;
SrcCallSiteOffsets.reserve(Item.getNumSources());
std::map<CallInst *, std::set<WorkItem::size_type>> CallSiteSrcIds;
// This loop fills `SrcCallSiteOffsets` so that its n-th element will point
// to the `CallSiteOffsetMap` associated with the n-th source of the Value
// that we're considering.
WorkItem::size_type SI = 0;
for (const Use *Src : Item.sources()) {
Value *SrcVal = Src->get();
revng_log(CSVAccessLog,
"SrcVal: " << SrcVal << " : " << dumpToString(SrcVal));
const CallSiteOffsetMap &CallSiteOffset = ValueCallSiteOffsets.at(SrcVal);
// The `CallSiteOffsetMap` associated with `SrcVal` is pushed back into
// `SrcCallSiteOffsets`, into position `SI`.
SrcCallSiteOffsets.push_back(&CallSiteOffset);
// Then, this loop inserts the source index `SI` into the set of source
// indices associated with the call site `C.first`
for (const auto &C : CallSiteOffset)
CallSiteSrcIds[C.first].insert(SI);
++SI;
}
// Here `SrcCallSiteOffsets[i]` contains a pointer the the
// `CallSiteOffsetMap` associated with the source number `i` of the analyzed
// `Value`.
// Here, for a given call site `C` in `root` the value
// `CallSiteSrcIds.at(C)` is the set of source indices for which the value
// currently analyzed is reached from the call site `C`.
auto Call = dyn_cast<CallInst>(ItemVal);
const Function *Callee = Call ? getCallee(Call) : nullptr;
if (Callee != nullptr and Callee->getIntrinsicID() == Intrinsic::memcpy) {
// Separately handle Intrinsic::memcpy;
// Calls to Intrinsic::memcpy are a special case.
// Given that they don't generate any Value, they cannot be pushed on the
// worklist as a consequence of the backward exploration towards sources.
// For this reason, if we reach a point where we're trying to compute the
// offsets from the sources of a call to Intrinsic::memcpy it must be the
// memcpy where we started from and we don't really want to propagate from
// the return to the call site, but we want to compute the result and
// store it in the proper map.
revng_log(CSVAccessLog,
"MAP Intrinsic::memcpy: " << ItemVal << " : "
<< dumpToString(ItemVal));
revng_assert(isa<ConstantInt>(Call->getArgOperand(2)));
ValueCallSiteOffsetMap &VCSOffsets = IsLoad ? LoadCallSiteOffsets :
StoreCallSiteOffsets;
Value *PtrOp = IsLoad ? Call->getArgOperand(1) : Call->getArgOperand(0);
auto CSOff = std::make_pair(ItemVal, ValueCallSiteOffsets.at(PtrOp));
bool New = VCSOffsets.insert(CSOff).second;
revng_assert(New);
} else {
// This loop iterates over each call instruction in `CallSiteSrcIds`,
// and, for all the source indices associated to that call site, it
// combines all of the `CSVOffsets` to compute the new `CSVOffsets` of the
// node that we're popping.
for (const auto &CallSrc : CallSiteSrcIds) {
std::optional<CSVOffsets> New;
CallInst *TheCall = CallSrc.first;
for (const auto I : CallSrc.second) {
revng_log(CSVAccessLog,
"AT: " << TheCall << " : " << dumpToString(TheCall));
const CSVOffsets &SrcOffset = SrcCallSiteOffsets[I]->at(TheCall);
if (New) {
New->combine(SrcOffset);
} else {
revng_log(CSVAccessLog, "NEW");
New = SrcOffset;
}
revng_log(CSVAccessLog, "SrcOffsets : " << SrcOffset);
revng_log(CSVAccessLog, "New Offsets: " << *New);
}
revng_log(CSVAccessLog,
"MAP JOIN: " << ItemVal << " : " << dumpToString(ItemVal)
<< "\n " << *New);
// Insert the `New` in the `ValueCallSiteOffsets`
ValueCallSiteOffsets[ItemVal][TheCall] = std::move(*New);
revng_log(CSVAccessLog,
"CallSite: " << TheCall << " : " << dumpToString(TheCall)
<< "\n "
<< ValueCallSiteOffsets.at(ItemVal).at(TheCall));
}
}
tryRemoveCurCrossedCallSite(Item);
} else if (auto *Instr = dyn_cast<Instruction>(ItemVal)) {
revng_log(CSVAccessLog, "POP INST");
const auto OpCode = Instr->getOpcode();
switch (OpCode) {
case Instruction::ZExt:
case Instruction::SExt:
case Instruction::Trunc:
case Instruction::PtrToInt:
case Instruction::IntToPtr:
case Instruction::BitCast: {
revng_assert(Item.getNumSources() == Instr->getNumOperands());
revng_log(CSVAccessLog,
"MAP CAST: " << ItemVal << " : " << dumpToString(ItemVal));
Value *Op = Instr->getOperand(0);
ValueCallSiteOffsets[ItemVal] = ValueCallSiteOffsets.at(Op);
} break;
case Instruction::Sub:
case Instruction::Add: {
revng_assert(Item.getNumSources() == Instr->getNumOperands());
revng_log(CSVAccessLog, "Add/Sub");
AddSubFolder.fold(Item, ValueCallSiteOffsets);
} break;
case Instruction::Shl:
case Instruction::AShr:
case Instruction::LShr:
case Instruction::Mul:
case Instruction::URem:
case Instruction::SRem:
case Instruction::SDiv:
case Instruction::UDiv: {
revng_assert(Item.getNumSources() == Instr->getNumOperands());
revng_log(CSVAccessLog, "NumericFold");
NumericFolder.fold(Item, ValueCallSiteOffsets);
} break;
case Instruction::GetElementPtr: {
revng_assert(Item.getNumSources() == Instr->getNumOperands());
revng_log(CSVAccessLog, "GEP");
GEPFolder.fold(Item, ValueCallSiteOffsets);
} break;
case Instruction::Load: {
revng_assert(Item.getNumSources() == Instr->getNumOperands());
Value *AddressValue = cast<LoadInst>(Instr)->getPointerOperand();
auto LoadCSOff = std::make_pair(ItemVal,
ValueCallSiteOffsets.at(AddressValue));
bool New = LoadCallSiteOffsets.insert(LoadCSOff).second;
if (CSVAccessLog.isEnabled()) {
revng_log(CSVAccessLog, "Load " << dumpToString(Instr));
for (const auto &CS2O : LoadCSOff.second) {
revng_log(CSVAccessLog, "CallSite: ");
if (CS2O.first)
revng_log(CSVAccessLog, dumpToString(CS2O.first));
else
revng_log(CSVAccessLog, "nullptr");
revng_log(CSVAccessLog, CS2O.second);
}
}
revng_assert(New);
} break;
case Instruction::Store: {
revng_assert(Item.getNumSources() == 1);
Value *AddressValue = cast<StoreInst>(Instr)->getPointerOperand();
auto StoreCSOff = std::make_pair(ItemVal,
ValueCallSiteOffsets.at(AddressValue));
bool New = StoreCallSiteOffsets.insert(StoreCSOff).second;
if (CSVAccessLog.isEnabled()) {
revng_log(CSVAccessLog, "Store " << dumpToString(Instr));
for (const auto &CS2O : StoreCSOff.second) {
revng_log(CSVAccessLog, "CallSite: ");
if (CS2O.first)
revng_log(CSVAccessLog, dumpToString(CS2O.first));
else
revng_log(CSVAccessLog, "nullptr");
revng_log(CSVAccessLog, CS2O.second);
}
}
revng_assert(New);
} break;
default:
revng_abort(dumpToString(Instr).data());
}
} else {
revng_abort();
}
}
void CPUSAOA::insertCallSiteOffset(Value *V, CSVOffsets &&Offset) {
revng_log(CSVAccessLog, "MAP INSERT: " << V);
// If CrossedCallSites is empty we haven't reached the root function during
// the backward exploration, so the only active call site is nullptr.
// The same holds if we're inserting the offset for a ConstantInt. The problem
// with constants is that they are not propagated through the call graph, but
// they are in a global context and they infect all the places where they're
// used independently of the call sites crossed during the exploration. For
// this reason, if we accumulate all the call sites for the constants we may
// end up in situation where on a given constant we have lots of call sites in
// the map, but all with the same CSVOffsets. This is bad for two reasons:
// 1) it increases the size of the map for no reason;
// 2) it potentially propagates wrong call sites where the constants are used.
// For this reason we used this workaround, to only insert null call sites for
// constants.
if (CrossedCallSites.empty() or isa<ConstantInt>(V)) {
ValueCallSiteOffsets[V][nullptr] = Offset;
revng_log(CSVAccessLog, "CallSite: nullptr\n " << Offset);
} else {
// In all the other cases use the active set of crossed call sites
for (const auto &Call : CrossedCallSites) {
ValueCallSiteOffsets[V][Call] = Offset;
revng_log(CSVAccessLog, "CallSite: " << Call << "\n " << Offset);
}
}
}
OptCSVOffsets
CPUSAOA::getOffsetsOrExploreSrc(Value *V, WorkItem &Item, bool IsLoad) const {
if (auto *Call = dyn_cast<CallInst>(V)) {
revng_log(CSVAccessLog, "CALL: " << dumpToString(Call));
Item = WorkItem(Call, IsLoad, Lazy, LoadMDKind, StoreMDKind);
} else if (auto *Arg = dyn_cast<Argument>(V)) {
revng_log(CSVAccessLog, "ARG: " << dumpToString(Arg));
Item = WorkItem(Arg, ReachableFunctions, Lazy, LoadMDKind, StoreMDKind);
} else if (auto *Instr = dyn_cast<Instruction>(V)) {
revng_log(CSVAccessLog, "INST: " << dumpToString(Instr));
const auto OpCode = Instr->getOpcode();
switch (OpCode) {
case Instruction::Load: {
revng_log(CSVAccessLog, "LOAD");
const auto *Load = cast<const LoadInst>(Instr);
const Value *Ptr = Load->getPointerOperand()->stripPointerCasts();
if (const auto *CSV = dyn_cast<const GlobalVariable>(Ptr)) {
revng_log(CSVAccessLog, "GLOBAL");
if (CSV == CPUStatePtr) {
revng_log(CSVAccessLog, "ENV");
return CSVOffsets(CSVOffsets::Kind::KnownInPtr, 0);
} else {
revng_log(CSVAccessLog, "NOT-ENV");
return CSVOffsets(CSVOffsets::Kind::Unknown);
}
} else {
revng_log(CSVAccessLog, "NOT-GLOBAL");
return CSVOffsets(CSVOffsets::Kind::Unknown);
}
}
case Instruction::Alloca:
revng_log(CSVAccessLog, "ALLOCA");
return CSVOffsets(CSVOffsets::Kind::Unknown);
case Instruction::Or:
case Instruction::And:
case Instruction::ICmp:
revng_log(CSVAccessLog, "CMP");
return CSVOffsets(CSVOffsets::Kind::Unknown);
case Instruction::Store:
revng_abort();
default:
break;
}
// If we reach this point the CSVOffsets of this instruction are not known
Item = WorkItem(Instr);
} else if (const auto *IntConst = dyn_cast<const ConstantInt>(V)) {
int64_t Offset = IntConst->getSExtValue();
revng_log(CSVAccessLog, "CONST: " << Offset);
return CSVOffsets(CSVOffsets::Kind::Numeric, Offset);
} else {
revng_abort();
}
return OptCSVOffsets();
}
bool CPUSAOA::exploreImmediateSources(Value *V, bool IsLoad) {
// Try to get new unexplored sources for V.
WorkItem NewItem;
{
auto ConstKnownOffsets = getOffsetsOrExploreSrc(V, NewItem, IsLoad);
if (ConstKnownOffsets.has_value()) {
revng_log(CSVAccessLog, "ConstantOffset");
// If we reach this point, V only has a constant know CSVOffsets and does
// not really have sources that must be explored. In this case we can just
// insert the ConstKnownOffsets in the map and we're done.
insertCallSiteOffset(V, std::move(*ConstKnownOffsets));
return false;
}
}
revng_log(CSVAccessLog, "New!: " << NewItem);
Value *NewItemV = NewItem.val();
if (isInExploration(NewItemV)) {
revng_log(CSVAccessLog, "IS RECURSIVE");
const ConstValuePtrSet &Tainted = TaintedAccesses.TaintedValues;
if (const Argument *Arg = dyn_cast<Argument>(NewItemV)) {
revng_assert(Tainted.contains(Arg));
revng_assert(Arg->getArgNo() == 0);
const Function *Fun = Arg->getParent();
revng_assert(CpuLoop != nullptr);
revng_assert(CpuLoop->arg_size());
revng_assert(Arg->getType() == CpuLoop->arg_begin()->getType());
auto WLIt = WorkList.cbegin();
auto WLEnd = WorkList.cend();
bool FoundRecursion = false;
for (; WLIt != WLEnd; ++WLIt) {
if (Arg != WLIt->val())
continue;
FoundRecursion = true;
revng_log(CSVAccessLog, "Close recursion");
Value *CurSrcVal = WLIt->currentSourceValue();
revng_assert(CurSrcVal != Arg);
CSVOffsets NewOffsets = CSVOffsets(CSVOffsets::Kind::KnownInPtr, 0);
insertCallSiteOffset(CurSrcVal, std::move(NewOffsets));
Value *NextSrcVal = WLIt->nextSourceValue();
if (nullptr == NextSrcVal)
break;
revng_log(CSVAccessLog,
"Has unresolved source: " << dumpToString(NextSrcVal));
revng_assert(NextSrcVal != Arg);
WorkItem::size_type NextSrcId = WLIt->getSourceIndex() + 1;
NewItem.setSourceIndex(NextSrcId);
if (tryPush(std::move(NewItem)))
return true;
}
revng_assert(FoundRecursion);
} else {
revng_assert(!Tainted.contains(NewItemV));
for (const Use *U : NewItem.sources())
insertCallSiteOffset(U->get(), CSVOffsets(CSVOffsets::Kind::Unknown));
}
} else {
for (const auto &Group : llvm::enumerate(NewItem.sources())) {
revng_log(CSVAccessLog, "Src: " << dumpToString(Group.value()->get()));
revng_log(CSVAccessLog, "SrcId: " << Group.index());
// Adjust the SourceIndex, to set the correct Source
auto SrcId = Group.index();
NewItem.setSourceIndex(SrcId);
if (tryPush(std::move(NewItem)))
return true;
}
}
// If we reach this point the current Value V only has sources that were
// already explored.
if (NewItem.getNumSources()) {
revng_log(CSVAccessLog, "DONE");
computeOffsetsFromSources(NewItem, IsLoad);
}
return false;
}
static bool callsBuiltinMemcpy(const Instruction *TheCall) {
const Function *Callee = getCallee(TheCall);
return Callee != nullptr and Callee->getIntrinsicID() == Intrinsic::memcpy;
}
void CPUSAOA::analyzeAccess(Instruction *LoadOrStore, bool IsLoad) {
// This analysis starts from the Instruction LoadOrStore and works in two
// alternate steps:
// 1) it iterates backward, looking for all the values that generate their
// pointer operands;
// 2) as soon as the backward exploration reaches the leaves (i.e. the initial
// values that are used as building blocks for the computation) it starts
// working forward. At each step of the forward propagation it tries to
// constant-fold the sources of the current value. If all the offsets of all
// the sources are known they are constant folded and the analysis keeps
// working forward. Otherwise, if there is a source that it still unexplored
// (i.e. it has no known offsets), the analysis starts working backward again,
// until also the unexplored source is resolved and can be constant folded.
// Initialization
if (not callsBuiltinMemcpy(LoadOrStore))
push(WorkItem(LoadOrStore));
else
push(WorkItem(cast<CallInst>(LoadOrStore),
IsLoad,
Lazy,
LoadMDKind,
StoreMDKind));
while (not WorkList.empty()) {
const auto Size = WorkList.size();
Value *CurSrcVal = WorkList.back().currentSourceValue();
if (CSVAccessLog.isEnabled()) {
const auto *CurVal = WorkList.back().val();
revng_log(CSVAccessLog,
"Val : " << CurVal << " : " << dumpToString(CurVal));
revng_log(CSVAccessLog,
"Src : " << CurSrcVal << " : " << dumpToString(CurSrcVal));
}
// Explore CurSrcVal's immediate sources (going backward)
// If we the exploration succeeded we have something new on the WorkList and
// we want to keep exploring back
if (exploreImmediateSources(CurSrcVal, IsLoad))
continue;
revng_log(CSVAccessLog, "not grown");
// If we didn't push anything, we are done exploring backward the current
// source and we want to explore backward the other sources of this value
if (Size == WorkList.size())
if (selectNextSource(WorkList.back()))
continue;
revng_log(CSVAccessLog, "Done");
// If we reach this point we have finished exploring all the sources of
// the item that is currently on top of the WorkList.
// The backward propagation is complete for now.
// We want to fold the results of the sources on the Item, store the
// result in the OffsetMap, and then pop the Item
do {
const WorkItem &Item = WorkList.back();
if (CSVAccessLog.isEnabled()) {
const auto *Val = Item.val();
revng_log(CSVAccessLog,
"TopItemVal: " << Val << " : " << dumpToString(Val));
const auto *SrcVal = Item.currentSourceValue();
revng_log(CSVAccessLog,
"CurSrc : " << SrcVal << " : " << dumpToString(SrcVal));
}
// Constant fold the finished value and pop it.
computeOffsetsFromSources(Item, IsLoad);
pop();
} while (not WorkList.empty()
and WorkList.back().nextSourceValue() == nullptr);
if (not WorkList.empty())
selectNextSource(WorkList.back());
}
}
template<bool IsLoad>
void CPUSAOA::computeAggregatedOffsets() {
const InstrPtrSet &Tainted = IsLoad ? TaintedAccesses.TaintedLoads :
TaintedAccesses.TaintedStores;
ValueCallSiteOffsetMap &AccessCSOffsets = IsLoad ? LoadCallSiteOffsets :
StoreCallSiteOffsets;
CallSiteOffsetMap &CallSiteOffsets = IsLoad ? CallSiteLoadOffsets :
CallSiteStoreOffsets;
AccessOffsetMap &AccessOffsets = IsLoad ? LoadOffsets : StoreOffsets;
for (std::pair<Value *const, CallSiteOffsetMap> &ACSO : AccessCSOffsets) {
// This is the load/store that actually accesses the CPU State
Value *I = ACSO.first;
auto DL = M.getDataLayout();
bool IsInstr = isa<Instruction>(I);
bool IsCorrectAccessType = IsLoad ? isa<LoadInst>(I) : isa<StoreInst>(I);
bool IsCallToBuiltinMemcpy = callsBuiltinMemcpy(dyn_cast<Instruction>(I));
revng_assert(IsInstr and (IsCorrectAccessType or IsCallToBuiltinMemcpy));
auto *Instr = dyn_cast<Instruction>(I);
revng_assert(Tainted.contains(Instr));
int64_t AccessSize;
if (IsCallToBuiltinMemcpy) {
auto Call = cast<CallInst>(I);
auto SizeParam = cast<ConstantInt>(Call->getArgOperand(2));
AccessSize = SizeParam->getSExtValue();
} else if (IsLoad) {
auto *Load = cast<LoadInst>(Instr);
AccessSize = DL.getTypeAllocSize(Load->getType());
} else {
auto Store = cast<StoreInst>(Instr);
AccessSize = DL.getTypeAllocSize(Store->getValueOperand()->getType());
}
revng_assert(AccessSize != 0);
CallSiteOffsetMap &CallSiteMap = ACSO.second;
for (std::pair<CallInst *const, CSVOffsets> &CSO : CallSiteMap) {
CallInst *const Call = CSO.first;
CSVOffsets &O = CSO.second;
revng_assert(O.isPtr());
bool Inserted;
// Compute AccessOffsets, i.e. the set of offsets accessed by each access
{
AccessOffsetMap::iterator AccessOffsetIt;
auto Offset = std::make_pair(Instr, O);
std::tie(AccessOffsetIt, Inserted) = AccessOffsets.insert(Offset);
if (not Inserted)
AccessOffsetIt->second.combine(O);
}
// Compute CallSiteOffsets, i.e. the set of offsets that might be accessed
// from a given call in root.
// This is a little more tricky than computing AccessOffsets, since here,
// when we collapse on the call site, we lose the information on the
// specific instruction that caused a given offset to be computed, hence
// also losing the size of the access. For this reason here we have to
// take into account the sizes of all the accesses.
{
OptCSVOffsets New;
if (not O.hasOffsetSet()) {
New = O;
} else {
revng_assert(O.size());
std::set<int64_t> FineGrainedOffsets;
// Now compute the fine-grained offsets
for (const int64_t Coarse : O) {
int64_t Refined = Coarse;
int64_t End = Coarse + AccessSize;
while (Refined < End) {
unsigned InternalOffset = 0;
GlobalVariable *AccessedVar;
std::tie(AccessedVar,
InternalOffset) = Variables->getByEnvOffset(Refined);
int64_t SizeAtOffset = 0;
if (AccessedVar != nullptr) {
Type *AccessedTy = AccessedVar->getValueType();
SizeAtOffset = DL.getTypeAllocSize(AccessedTy) - InternalOffset;
revng_assert(SizeAtOffset > 0);
FineGrainedOffsets.insert(Refined - InternalOffset);
CSVAccessLog << "Value: " << I << DoLog;
CSVAccessLog << "Insert Refined: " << Refined << DoLog;
} else {
// Skip padding one byte at a time, without adding offsets
SizeAtOffset = 1;
}
revng_assert(SizeAtOffset != 0);
Refined += SizeAtOffset;
}
}
New = CSVOffsets(O.getKind(), FineGrainedOffsets);
}
// Finally insert them or combine them
CallSiteOffsetMap::iterator CallOffsetIt;
std::tie(CallOffsetIt,
Inserted) = CallSiteOffsets.insert({ Call, *New });
if (not Inserted)
CallOffsetIt->second.combine(*New);
}
}
}
}
bool CPUSAOA::run() {
// Analyze load and store
for (Instruction *I : TaintedAccesses.TaintedLoads)
analyzeAccess(I, true);
for (Instruction *I : TaintedAccesses.TaintedStores)
analyzeAccess(I, false);
if (CSVAccessLog.isEnabled()) {
TaintLog << "== ACCESS ANALYSIS RESULTS ==\n";
TaintLog << "== Loads ==\n";
for (Instruction *LoadOrStore : TaintedAccesses.TaintedLoads) {
TaintLog << "INSTRUCTION: " << LoadOrStore << DoLog;
TaintLog << dumpToString(LoadOrStore) << DoLog;
TaintLog.indent(4);
for (const auto &CSO : LoadCallSiteOffsets.at(LoadOrStore)) {
TaintLog << "CallSite: " << CSO.first << '\n';
if (CSO.first != nullptr)
TaintLog << dumpToString(CSO.first);
TaintLog << DoLog;
TaintLog << CSO.second << '\n';
}
TaintLog.unindent(4);
TaintLog << DoLog;
}
TaintLog << "== Stores ==\n";
for (Instruction *LoadOrStore : TaintedAccesses.TaintedStores) {
TaintLog << "INSTRUCTION: " << LoadOrStore << DoLog;
TaintLog << dumpToString(LoadOrStore) << DoLog;
TaintLog.indent(4);
for (const auto &CSO : StoreCallSiteOffsets.at(LoadOrStore)) {
TaintLog << "CallSite: " << CSO.first << '\n';
if (CSO.first != nullptr)
TaintLog << dumpToString(CSO.first);
TaintLog << DoLog;
TaintLog << CSO.second << '\n';
}
TaintLog.unindent(4);
TaintLog << DoLog;
}
TaintLog << DoLog;
}
// ValueCallSiteOffset is not needed anymore here, because it's only used
// across different calls to analyzeAccess to optimize the runtime avoiding
// multiple iterations on the same Values.
ValueCallSiteOffsets = {};
// Aggregate the results:
// - from LoadCallSiteOffsets to CallSiteLoadOffsets and LoadOffsets
// - from StoreCallSiteOffsets to CallSiteStoreOffsets and StoreOffsets
computeAggregatedOffsets</* IsLoad = */ true>();
computeAggregatedOffsets</* IsLoad = */ false>();
cleanup();
return not TaintedAccesses.empty();
}
class CPUStateAccessFixer {
private:
using Pair = AccessOffsetMap::value_type;
private:
// A reference to the analyzed Module
const Module &M;
VariableManager *Variables;
// References to the maps that were filled by CPUStateAccessAnalysis.
// Every map maps an Instruction to the CSVOffset representing all the
// possible offsets that are accessed by that Instruction, being it either a
// load, a store or a call to Intrinsic::memcpy.
// We hold two separate maps, one for loads and one for stores, so that calls
// to memcpy can be in both maps, with different associated offsets.
const AccessOffsetMap &CSVLoadOffsetMap;
const AccessOffsetMap &CSVStoreOffsetMap;
std::vector<Instruction *> InstructionsToRemove;
public:
CPUStateAccessFixer(const Module &Mod,
VariableManager *V,
const AccessOffsetMap &L,
const AccessOffsetMap &S) :
M(Mod),
Variables(V),
CSVLoadOffsetMap(L),
CSVStoreOffsetMap(S),
DL(Mod.getDataLayout()),
EnvStructSize(DL.getTypeAllocSize(V->getCPUStateType())),
Builder(Mod.getContext()),
Int64Ty(IntegerType::getInt64Ty(M.getContext())),
SizeOfEnv(ConstantInt::get(Int64Ty, APInt(64, EnvStructSize, true))),
Zero(ConstantInt::get(Int64Ty, APInt(64, 0, true))),
CPUStatePtr(Mod.getGlobalVariable("env")) {}
public:
bool run();
private:
template<bool IsLoad>
std::tuple<Instruction *, Type *, Value *>
setupOutEnvAccess(Instruction *AccessToFix);
template<bool IsLoad>
void correctCPUStateAccesses();
void setupLoadInEnv(Instruction *LoadToFix,
int64_t EnvOffset,
SwitchInst *Switch,
BasicBlock *NextBB,
PHINode *Phi);
void setupStoreInEnv(Instruction *LoadToFix,
int64_t EnvOffset,
SwitchInst *Switch,
BasicBlock *NextBB);
template<bool IsLoad>
void fixAccess(const Pair &IOff);
private:
const DataLayout &DL;
int64_t EnvStructSize;
IRBuilder<> Builder;
Type *Int64Ty;
Constant *SizeOfEnv;
Constant *Zero;
Value *CPUStatePtr;
};
static Value *getLoadAddressValue(Instruction *I) {
auto OpCode = I->getOpcode();
Value *Address = nullptr;
switch (OpCode) {
case Instruction::Load: {
Address = cast<LoadInst>(I)->getPointerOperand();
} break;
case Instruction::Call: {
auto *Call = cast<CallInst>(I);
Function *Callee = getCallee(Call);
// We only support memcpys where the last parameter is constant
revng_assert(Callee != nullptr
and (Callee->getIntrinsicID() == Intrinsic::memcpy
and isa<ConstantInt>(Call->getArgOperand(2))));
Address = Call->getArgOperand(1);
} break;
default:
revng_abort();
}
return Address;
}
static Type *getLoadedType(Instruction *I) {
if (auto Load = dyn_cast<LoadInst>(I)) {
return Load->getType();
}
return nullptr;
}
static Value *getStoreAddressValue(Instruction *I) {
auto OpCode = I->getOpcode();
Value *Address = nullptr;
switch (OpCode) {
case Instruction::Store: {
Address = cast<StoreInst>(I)->getPointerOperand();
} break;
case Instruction::Call: {
auto *Call = cast<CallInst>(I);
Function *Callee = getCallee(Call);
// We only support memcpys where the last parameter is constant
revng_assert(Callee != nullptr
and (Callee->getIntrinsicID() == Intrinsic::memcpy
and isa<ConstantInt>(Call->getArgOperand(2))));
Address = Call->getArgOperand(0);
} break;
default:
revng_abort();
}
return Address;
}
static Type *getStoredType(Instruction *I) {
if (auto *Store = dyn_cast<StoreInst>(I)) {
return Store->getValueOperand()->getType();
}
return nullptr;
}
static ConstantInt *getConstantOffset(Type *Int64Ty, int64_t O) {
auto *EnvOffsetConst = ConstantInt::get(Int64Ty, APInt(64, O, true));
return cast<ConstantInt>(EnvOffsetConst);
}
template<bool IsLoad>
std::tuple<Instruction *, Type *, Value *>
CPUStateAccessFixer::setupOutEnvAccess(Instruction *AccessToFix) {
LLVMContext &Context = M.getContext();
BasicBlock *AccessToFixBB = AccessToFix->getParent();
Function *F = AccessToFixBB->getParent();
auto InstrIt = AccessToFix->getIterator();
revng_assert(InstrIt != AccessToFixBB->end());
revng_assert(std::next(InstrIt) != AccessToFixBB->end());
// Create a new block NextBB and move there all the instructions after
// the access
BasicBlock *NextBB = AccessToFixBB->splitBasicBlock(InstrIt);
AccessToFixBB->getTerminator()->eraseFromParent();
revng_assert(not NextBB->empty());
// Create a new block OutAccessBB only for accesses outside env, and
// clone the accessing instruction in there. This clone of the
// accessing instruction in the OutAccessBB will be leaved untouched
// by the substitution performed later.
BasicBlock *OutAccessBB = BasicBlock::Create(Context, "OutAccess", F);
Builder.SetInsertPoint(OutAccessBB);
BranchInst *OutToNextBranchInst = Builder.CreateBr(NextBB);
Instruction *OutAccess = AccessToFix->clone();
OutAccess->insertBefore(OutToNextBranchInst);
// Create a new block InAccessBB only for accesses inside env (if any).
// The accessing instruction is cloned into the new InAccessBB
// and we insert a branch instruction to the NextBB.
BasicBlock *InAccessBB = BasicBlock::Create(Context, "InAccess", F);
Builder.SetInsertPoint(InAccessBB);
BranchInst *InToNextBranchInst = Builder.CreateBr(NextBB);
Instruction *InAccessToFix = AccessToFix->clone();
InAccessToFix->insertBefore(InToNextBranchInst);
// Create a conditional branch to jump to InAccessBB if the access is
// going to be in env, or to OutAccessBB if the access is going to be
// out of env
Value *Address = IsLoad ? getLoadAddressValue(AccessToFix) :
getStoreAddressValue(AccessToFix);
Builder.SetInsertPoint(AccessToFixBB);
Value *OffsetValue = Builder.CreatePtrToInt(Address, Int64Ty);
Value *GEZero = Builder.CreateICmpSGE(OffsetValue, Zero);
Value *LTSizeOf = Builder.CreateICmpSLT(OffsetValue, SizeOfEnv);
Value *IsInCSV = Builder.CreateOr(GEZero, LTSizeOf);
Builder.CreateCondBr(IsInCSV, InAccessBB, OutAccessBB);
if (IsLoad) {
Type *LoadedType = getLoadedType(AccessToFix);
if (LoadedType != nullptr) {
Builder.SetInsertPoint(&NextBB->front());
PHINode *PN = Builder.CreatePHI(LoadedType, 2);
AccessToFix->replaceAllUsesWith(PN);
PN->addIncoming(OutAccess, OutAccessBB);
PN->addIncoming(InAccessToFix, InAccessBB);
}
return std::make_tuple(InAccessToFix, LoadedType, OffsetValue);
}
return std::make_tuple(InAccessToFix, nullptr, OffsetValue);
}
void CPUStateAccessFixer::setupLoadInEnv(Instruction *LoadToFix,
int64_t EnvOffset,
SwitchInst *Switch,
BasicBlock *NextBB,
PHINode *Phi) {
LLVMContext &Context = M.getContext();
Function *F = LoadToFix->getFunction();
auto *OffsetConstInt = getConstantOffset(Int64Ty, EnvOffset);
BasicBlock *CaseBlock = BasicBlock::Create(Context, "CaseInLoad", F);
Builder.SetInsertPoint(CaseBlock);
BranchInst *Break = Builder.CreateBr(NextBB);
Instruction *Clone = LoadToFix->clone();
Clone->insertBefore(Break);
bool Ok = false;
Builder.SetInsertPoint(Clone);
switch (LoadToFix->getOpcode()) {
case Instruction::Load: {
Type *OriginalLoadedType = Clone->getType();
unsigned Size = DL.getTypeAllocSize(OriginalLoadedType);
revng_assert(Size != 0);
auto *Loaded = Variables->loadFromEnvOffset(Builder, Size, EnvOffset);
Ok = Loaded != nullptr;
if (Ok) {
Type *LoadedType = Loaded->getType();
if (LoadedType != OriginalLoadedType) {
unsigned LoadedSize = DL.getTypeAllocSize(LoadedType);
revng_assert(LoadedSize == Size);
Loaded = Builder.CreateIntToPtr(Loaded, OriginalLoadedType);
}
Switch->addCase(OffsetConstInt, CaseBlock);
// Add an incoming edge for the PHI after the switch if necessary.
if (Phi != nullptr)
Phi->addIncoming(Loaded, CaseBlock);
Clone->replaceAllUsesWith(Loaded);
InstructionsToRemove.push_back(Clone);
} else {
eraseFromParent(CaseBlock);
CaseBlock = nullptr; // Prevent this from being used
}
} break;
case Instruction::Call: {
CallInst *Call = cast<CallInst>(Clone);
Ok = Variables->memcpyAtEnvOffset(Builder, Call, EnvOffset, true);
if (Ok) {
InstructionsToRemove.push_back(Clone);
Switch->addCase(OffsetConstInt, CaseBlock);
} else {
eraseFromParent(CaseBlock);
CaseBlock = nullptr; // Prevent this from being used
}
} break;
default:
revng_abort();
}
}
void CPUStateAccessFixer::setupStoreInEnv(Instruction *StoreToFix,
int64_t EnvOffset,
SwitchInst *Switch,
BasicBlock *NextBB) {
LLVMContext &Context = M.getContext();
Function *F = StoreToFix->getFunction();
auto *OffsetConstInt = getConstantOffset(Int64Ty, EnvOffset);
BasicBlock *CaseBlock = BasicBlock::Create(Context, "CaseInStore");
CaseBlock->insertInto(F);
Builder.SetInsertPoint(CaseBlock);
BranchInst *Break = Builder.CreateBr(NextBB);
Instruction *Clone = StoreToFix->clone();
Clone->insertBefore(Break);
bool Ok = false;
Builder.SetInsertPoint(Clone);
switch (StoreToFix->getOpcode()) {
case Instruction::Store: {
auto *Store = cast<StoreInst>(Clone);
auto *V = Store->getValueOperand();
unsigned Size = DL.getTypeAllocSize(V->getType());
revng_assert(Size != 0);
Ok = Variables->storeToEnvOffset(Builder, Size, EnvOffset, V).has_value();
} break;
case Instruction::Call: {
CallInst *Call = cast<CallInst>(Clone);
Ok = Variables->memcpyAtEnvOffset(Builder, Call, EnvOffset, false);
} break;
default:
revng_abort();
}
if (Ok) {
InstructionsToRemove.push_back(Clone);
Switch->addCase(OffsetConstInt, CaseBlock);
} else {
eraseFromParent(CaseBlock);
}
}
template<bool IsLoad>
void CPUStateAccessFixer::correctCPUStateAccesses() {
auto &CSVAccessOffsetMap = IsLoad ? CSVLoadOffsetMap : CSVStoreOffsetMap;
auto &OtherCSVAccessOffsetMap = IsLoad ? CSVStoreOffsetMap : CSVLoadOffsetMap;
if (IsLoad)
FixAccessLog << "######## Fixing Loads ########" << DoLog;
else
FixAccessLog << "######## Fixing Stores ########" << DoLog;
Type *CharTy = IntegerType::getInt8Ty(M.getContext());
for (const Pair &IOff : CSVAccessOffsetMap) {
Instruction *const Instr = IOff.first;
auto It = OtherCSVAccessOffsetMap.find(Instr);
if (It != OtherCSVAccessOffsetMap.end()) {
revng_log(FixAccessLog, "Is memcpy");
if (IsLoad) {
revng_log(FixAccessLog, "Must be fixed NOW!");
// Decompose memcpy from env to env into two separate memcpy, the first
// to do the load, the second to do the store
auto *Call = cast<CallInst>(Instr);
Function *Memcpy = getCallee(Call);
revng_assert(Memcpy != nullptr
and (Memcpy->getIntrinsicID() == Intrinsic::memcpy
and isa<ConstantInt>(Call->getArgOperand(2))));
Value *MemcpySize = Call->getArgOperand(2);
Value *MemcpySrc = Call->getArgOperand(1);
Value *MemcpyDst = Call->getArgOperand(0);
Function *F = Instr->getFunction();
Builder.SetInsertPoint(&*F->getEntryBlock().begin());
AllocaInst *TmpBuffer = Builder.CreateAlloca(CharTy, MemcpySize);
revng_log(FixAccessLog,
"Created ALLOCA: " << TmpBuffer << " : "
<< dumpToString(TmpBuffer));
Builder.SetInsertPoint(Instr);
auto TmpAlign = MaybeAlign(TmpBuffer->getAlign());
auto AlignOne = MaybeAlign(1);
CallInst *MemcpyLoad = Builder.CreateMemCpy(TmpBuffer,
TmpAlign,
MemcpySrc,
AlignOne,
MemcpySize);
revng_log(FixAccessLog,
"Created LOAD: " << MemcpyLoad << " : "
<< dumpToString(MemcpyLoad));
CallInst *MemcpyStore = Builder.CreateMemCpy(MemcpyDst,
AlignOne,
TmpBuffer,
TmpAlign,
MemcpySize);
revng_log(FixAccessLog,
"Created STORE: " << MemcpyStore << " : "
<< dumpToString(MemcpyStore));
fixAccess</* IsLoad = */ true>({ MemcpyLoad, IOff.second });
fixAccess</* IsLoad = */ false>({ MemcpyStore, It->second });
revng_log(FixAccessLog,
"Queuing for erasure memcpy: " << Instr << " : "
<< dumpToString(Instr));
InstructionsToRemove.push_back(Instr);
} // else do nothing because we fix it only once with loads
continue;
}
fixAccess<IsLoad>(IOff);
}
}
template<bool IsLoad>
void CPUStateAccessFixer::fixAccess(const Pair &IOff) {
Instruction *const Instr = IOff.first;
const CSVOffsets &Offsets = IOff.second;
CSVOffsets::Kind OKind = Offsets.getKind();
FixAccessLog << "Fixing access: " << Instr
<< "\nCSVOffsets Kind: " << CSVOffsets::toString(OKind) << DoLog;
revng_assert(CSVOffsets::isPtr(OKind));
Function *F = Instr->getFunction();
Instruction *AccessToFix = Instr;
switch (OKind) {
default:
case CSVOffsets::Kind::Unknown:
case CSVOffsets::Kind::Numeric:
revng_abort();
case CSVOffsets::Kind::OutAndKnownInPtr:
case CSVOffsets::Kind::UnknownInPtr:
case CSVOffsets::Kind::OutAndUnknownInPtr:
case CSVOffsets::Kind::KnownInPtr: {
revng_log(FixAccessLog, "Before: " << dumpToString(F));
// This is necessary to get the correct debug info.
// Setting the insert point to an Instruction also updates the Builder
// to use its debug info until the insert point is set to a new
// instruction.
// Given that in the rest of the code we mostly use
// SetInsertPoint(BasicBlock *), which does not reset the debug info, we
// want to do it now, otherwise we might end up using the wrong debug
// info from an instruction of a previous iteration of this loop.
Builder.SetInsertPoint(Instr);
Value *Address = nullptr;
Type *LoadedType = nullptr; // This is not used if IsLoad is false
Type *StoredType = nullptr; // This is not used if IsLoad is true
if (IsLoad) {
Address = getLoadAddressValue(Instr);
LoadedType = getLoadedType(Instr);
} else {
Address = getStoreAddressValue(Instr);
StoredType = getStoredType(Instr);
}
Value *OffsetValue = nullptr;
if (CSVOffsets::isInOutPtr(OKind))
std::tie(AccessToFix,
LoadedType,
OffsetValue) = setupOutEnvAccess<IsLoad>(Instr);
revng_assert(AccessToFix != nullptr);
LLVMContext &Context = M.getContext();
QuickMetadata QMD(Context);
if (IsLoad) {
if (LoadedType != nullptr and LoadedType->isPointerTy()) {
FixAccessLog << "REPLACE!" << DoLog;
Constant *NullPtr = Constant::getNullValue(LoadedType);
AccessToFix->replaceAllUsesWith(NullPtr);
break; // out from the big switch to the verify and cleanup code
}
// TODO: Handle memcpy, not necessary for now
} else {
if (StoredType != nullptr and StoredType->isPointerTy()) {
FixAccessLog << "REPLACE!" << DoLog;
break; // out from the big switch to the verify and cleanup code
}
// TODO: Handle memcpy, not necessary for now
}
// filter out cases where a switch is not necessary
if (Offsets.size() == 1) {
int64_t Offset = *Offsets.begin();
Instruction *Clone = AccessToFix->clone();
Clone->insertAfter(AccessToFix);
AccessToFix->replaceAllUsesWith(Clone);
Builder.SetInsertPoint(Clone);
bool Ok = false;
switch (AccessToFix->getOpcode()) {
case Instruction::Load: {
if (IsLoad) {
Type *OriginalLoadedType = Clone->getType();
unsigned Size = DL.getTypeAllocSize(OriginalLoadedType);
revng_assert(Size != 0);
auto *Loaded = Variables->loadFromEnvOffset(Builder, Size, Offset);
Ok = Loaded != nullptr;
if (Ok) {
Type *LoadedType = Loaded->getType();
if (LoadedType != OriginalLoadedType) {
unsigned LoadedSize = DL.getTypeAllocSize(LoadedType);
revng_assert(LoadedSize == Size);
Loaded = Builder.CreateIntToPtr(Loaded, OriginalLoadedType);
}
Clone->replaceAllUsesWith(Loaded);
}
} else {
revng_abort();
}
} break;
case Instruction::Store: {
if (not IsLoad) {
auto *Store = cast<StoreInst>(Clone);
auto *V = Store->getValueOperand();
unsigned Size = DL.getTypeAllocSize(V->getType());
revng_assert(Size != 0);
Ok = Variables->storeToEnvOffset(Builder, Size, Offset, V)
.has_value();
} else {
revng_abort();
}
} break;
case Instruction::Call: {
CallInst *Call = cast<CallInst>(Clone);
Ok = Variables->memcpyAtEnvOffset(Builder, Call, Offset, IsLoad);
} break;
default:
revng_abort();
}
if (not Ok) {
Builder.SetInsertPoint(Clone);
CallInst *CallAbort = Builder.CreateCall(M.getFunction("abort"));
auto InvalidMDKind = Context.getMDKindID("revng.csaa.invalid.unique.in."
"access");
CallAbort->setMetadata(InvalidMDKind, QMD.tuple((uint32_t) 0));
} else {
InstructionsToRemove.push_back(Clone);
}
break; // out of the big switch to the verify and cleanup code
}
// Create a new block NextBB, after the Switch, and move there all the
// instructions after the access
BasicBlock *AccessToFixBB = AccessToFix->getParent();
auto InstrIt = AccessToFix->getIterator();
revng_assert(InstrIt != AccessToFixBB->end());
revng_assert(std::next(InstrIt) != AccessToFixBB->end());
BasicBlock *NextBB = AccessToFixBB->splitBasicBlock(std::next(InstrIt));
AccessToFixBB->getTerminator()->eraseFromParent();
revng_assert(not NextBB->empty());
revng_assert(std::next(InstrIt) == AccessToFixBB->end());
// If we're processing loads, add a PHI in NextBB if necessary
PHINode *Phi = nullptr;
if (IsLoad) {
if (LoadedType != nullptr) {
Builder.SetInsertPoint(&NextBB->front());
Phi = Builder.CreatePHI(LoadedType, Offsets.size());
AccessToFix->replaceAllUsesWith(Phi);
}
}
// Create the default BB for the switch, calling revng_abort()
BasicBlock *Default = BasicBlock::Create(Context, "DefaultInAccess", F);
Builder.SetInsertPoint(Default);
CallInst *CallAbort = Builder.CreateCall(M.getFunction("abort"));
auto UnexpectedInMDKind = Context.getMDKindID("revng.csaa.unexpected.in."
"access");
CallAbort->setMetadata(UnexpectedInMDKind, QMD.tuple((uint32_t) 0));
Builder.CreateUnreachable();
// Create the offset value to use as a variable for the switch if
// necessary
Builder.SetInsertPoint(AccessToFixBB);
if (OffsetValue == nullptr)
OffsetValue = Builder.CreatePtrToInt(Address, Int64Ty);
revng_assert(OffsetValue != nullptr);
if (CSVOffsets::isUnknownInPtr(OKind)) {
if (FixAccessLog.isEnabled()) {
++NumUnknown;
std::string Name = F->getName().str();
FunToNumUnknown[Name]++;
FunToUnknowns[Name].insert(dumpToString(AccessToFix));
}
SwitchInst *SwitchOffset = Builder.CreateSwitch(OffsetValue,
Default,
EnvStructSize);
for (int64_t CurrEnvOff = 0; CurrEnvOff < EnvStructSize; ++CurrEnvOff) {
if (IsLoad)
setupLoadInEnv(AccessToFix, CurrEnvOff, SwitchOffset, NextBB, Phi);
else
setupStoreInEnv(AccessToFix, CurrEnvOff, SwitchOffset, NextBB);
}
revng_assert(SwitchOffset->getNumCases() > 0);
break; // out from the switch, to the verify and cleanup code
}
revng_assert(Offsets.size() > 0);
SwitchInst *SwitchOffset = Builder.CreateSwitch(OffsetValue,
Default,
Offsets.size());
for (const int64_t CurrEnvOff : Offsets) {
if (IsLoad)
setupLoadInEnv(AccessToFix, CurrEnvOff, SwitchOffset, NextBB, Phi);
else
setupStoreInEnv(AccessToFix, CurrEnvOff, SwitchOffset, NextBB);
}
if (IsLoad) {
if (Phi != nullptr and Phi->getNumIncomingValues() == 0) {
Builder.SetInsertPoint(Phi);
CallInst *CallAbort = Builder.CreateCall(M.getFunction("abort"));
auto NeverValidInMDKind = Context.getMDKindID("revng.csaa.never.valid."
"in.load");
CallAbort->setMetadata(NeverValidInMDKind, QMD.tuple((uint32_t) 0));
Instruction *DisabledInLoad = AccessToFix->clone();
DisabledInLoad->insertBefore(Phi);
Phi->replaceAllUsesWith(DisabledInLoad);
InstructionsToRemove.push_back(Phi);
}
}
} break;
}
// Verify the transformation and cleanup the access to fix
revng_log(FixAccessLog, "After: " << dumpToString(F));
if (Instr != AccessToFix) {
if (FixAccessLog.isEnabled()) {
FixAccessLog << "Queuing for erasure AccessToFix: " << AccessToFix
<< DoLog;
FixAccessLog << dumpToString(AccessToFix) << DoLog;
}
InstructionsToRemove.push_back(AccessToFix);
}
if (FixAccessLog.isEnabled()) {
FixAccessLog << "Queuing for erasure Instr: " << Instr << DoLog;
FixAccessLog << dumpToString(Instr) << DoLog;
}
InstructionsToRemove.push_back(Instr);
}
bool CPUStateAccessFixer::run() {
if (CPUStatePtr == nullptr)
return false;
// Fix loads
correctCPUStateAccesses</* IsLoad = */ true>();
revng::verify(&M);
// Fix stores
correctCPUStateAccesses</* IsLoad = */ false>();
revng::verify(&M);
// Remove fixed accesses
for (Instruction *Instr : InstructionsToRemove)
eraseFromParent(Instr);
InstructionsToRemove.clear();
if (FixAccessLog.isEnabled()) {
FixAccessLog << "Num Unknowns: " << NumUnknown << DoLog;
for (const auto &Fun2Num : FunToNumUnknown)
FixAccessLog << Fun2Num.first << ": " << Fun2Num.second << DoLog;
for (const auto &Fun2Unknowns : FunToUnknowns)
for (const auto &U : Fun2Unknowns.second)
FixAccessLog << Fun2Unknowns.first << ": " << U << DoLog;
}
return true;
}
class CPUStateAccessAnalysis {
private:
const bool Lazy;
// A reference to the analyzed Module
const Module &M;
// A reference to the associated VariableManager
VariableManager *Variables;
// References to the maps that will be filled by this analysis.
// Every map maps an Instruction to the CSVOffset representing all the
// possible offsets that are accessed by that Instruction, being it either a
// load, a store or a call to Intrinsic::memcpy.
// We hold two separate maps, one for loads and one for stores, so that calls
// to memcpy can be in both maps, with different associated offsets.
AccessOffsetMap CSVLoadOffsetMap;
AccessOffsetMap CSVStoreOffsetMap;
const unsigned LoadMDKind;
const unsigned StoreMDKind;
// Helpers
const DataLayout &DL;
Type *Int64Ty;
Value *CPUStatePtr;
public:
CPUStateAccessAnalysis(const Module &Mod,
VariableManager *V,
const bool IsLazy) :
Lazy(IsLazy),
M(Mod),
Variables(V),
CSVLoadOffsetMap(),
CSVStoreOffsetMap(),
LoadMDKind(Mod.getContext().getMDKindID("revng.csvaccess.offsets.load")),
StoreMDKind(Mod.getContext().getMDKindID("revng.csvaccess.offsets.store")),
DL(Mod.getDataLayout()),
Int64Ty(llvm::IntegerType::getInt64Ty(Mod.getContext())),
CPUStatePtr(Mod.getGlobalVariable("env")) {}
public:
bool run();
private:
void forceEmptyMetadata(Function *RootFunction) const;
};
static void addAccessMetadata(const CallSiteOffsetMap &OffsetMap,
VariableManager *Variables,
QuickMetadata &QMD,
unsigned MDKind) {
for (auto &AccessOffsets : OffsetMap) {
CallInst *const CallSite = AccessOffsets.first;
if (CallSite == nullptr)
continue;
const CSVOffsets &Offsets = AccessOffsets.second;
revng_assert(Offsets.isPtr());
ConstantAsMetadata *UnknownAccess = nullptr;
MDTuple *AccessedVariablesTuple = nullptr;
SmallVector<Metadata *, 10> OffsetMetadata;
OffsetMetadata.reserve(Offsets.size());
std::set<GlobalVariable *> AccessedVars;
if (Offsets.isUnknownInPtr()) {
CSVAccessLog << "Unknown access to CSV" << DoLog;
UnknownAccess = QMD.get((uint32_t) 1);
AccessedVariablesTuple = QMD.tuple(OffsetMetadata);
} else {
UnknownAccess = QMD.get((uint32_t) 0);
for (const int64_t O : Offsets) {
CSVAccessLog << "CallSite: " << CallSite << DoLog;
CSVAccessLog << "Refined: " << O << DoLog;
GlobalVariable *AccessedVar = Variables->getByEnvOffset(O).first;
bool NewlyInserted = AccessedVars.insert(AccessedVar).second;
if (NewlyInserted) {
OffsetMetadata.push_back(QMD.get(AccessedVar));
}
CSVAccessLog << "Accessed Var: " << AccessedVar
<< " Offset: " << Variables->getByEnvOffset(O).second
<< DoLog;
}
AccessedVariablesTuple = QMD.tuple(OffsetMetadata);
}
SmallVector<Metadata *, 2> AccessMetadata = { UnknownAccess,
AccessedVariablesTuple };
CallSite->setMetadata(MDKind, QMD.tuple(AccessMetadata));
}
}
void CPUStateAccessAnalysis::forceEmptyMetadata(Function *RootFunction) const {
LLVMContext &Context = M.getContext();
QuickMetadata QMD(Context);
for (BasicBlock &BB : *RootFunction) {
for (Instruction &I : BB) {
if (isCallToHelper(&I)) {
if (I.getMetadata(LoadMDKind) == nullptr)
I.setMetadata(LoadMDKind,
MDTuple::get(Context,
{ QMD.get((uint32_t) 0),
MDTuple::get(Context, {}) }));
if (I.getMetadata(StoreMDKind) == nullptr)
I.setMetadata(StoreMDKind,
MDTuple::get(Context,
{ QMD.get((uint32_t) 0),
MDTuple::get(Context, {}) }));
}
}
}
}
bool CPUStateAccessAnalysis::run() {
if (CPUStatePtr == nullptr)
return false;
// Get the root Function
Function *RootFunction = M.getFunction("root");
revng_assert(RootFunction);
// Preprocessing: detect all the functions that are directly reachable from
// the RootFunction
auto ReachedFunctions = computeDirectlyReachableFunctions(RootFunction,
LoadMDKind,
StoreMDKind,
Lazy);
if (CSVAccessLog.isEnabled()) {
CSVAccessLog << "====== Reachable Functions ======";
for (const Function *F : ReachedFunctions)
CSVAccessLog << "\n" << F;
CSVAccessLog << DoLog;
}
// Start with a forward taint analysis, to detect all the tainted Values,
// and all the tainted loads and stores.
CSVAccessLog << "Before Taint Analysis" << DoLog;
const auto TaintResults = forwardTaintAnalysis(&M,
CPUStatePtr,
ReachedFunctions,
LoadMDKind,
StoreMDKind,
Lazy);
CSVAccessLog << "After Taint Analysis" << DoLog;
// If there are no tainted loads and stores we don't need to run the CPUSAOA.
if (TaintResults.TaintedLoads.empty()
and TaintResults.TaintedStores.empty()) {
forceEmptyMetadata(RootFunction);
return TaintResults.IllegalCalls.size();
}
if (TaintLog.isEnabled()) {
revng_log(TaintLog, "==== Tainted Loads ====");
for (const Instruction *I : TaintResults.TaintedLoads) {
revng_log(TaintLog, "In Function: " << I->getFunction()->getName());
revng_log(TaintLog, I << " : " << dumpToString(I));
}
revng_log(TaintLog, "==== Tainted Stores ====");
for (const Instruction *I : TaintResults.TaintedStores) {
revng_log(TaintLog, "In Function: " << I->getFunction()->getName());
revng_log(TaintLog, I << " : " << dumpToString(I));
}
revng_log(TaintLog, "==== Illegal Calls ====");
for (const Instruction *I : TaintResults.IllegalCalls) {
revng_log(TaintLog, "In Function: " << I->getFunction()->getName());
revng_log(TaintLog, I << " : " << dumpToString(I));
}
revng_log(TaintLog, "=======================");
}
CallSiteOffsetMap CallSiteLoadOffset;
CallSiteOffsetMap CallSiteStoreOffset;
auto AccessOffsetAnalysis = CPUSAOA(M,
CPUStatePtr,
RootFunction,
ReachedFunctions,
TaintResults,
Lazy,
LoadMDKind,
StoreMDKind,
Variables,
CSVLoadOffsetMap,
CSVStoreOffsetMap,
CallSiteLoadOffset,
CallSiteStoreOffset);
bool Found = AccessOffsetAnalysis.run();
if (Found) {
QuickMetadata QMD(M.getContext());
addAccessMetadata(CallSiteLoadOffset, Variables, QMD, LoadMDKind);
addAccessMetadata(CallSiteStoreOffset, Variables, QMD, StoreMDKind);
}
if (not Lazy) {
CPUStateAccessFixer CSVAccessFixer(M,
Variables,
CSVLoadOffsetMap,
CSVStoreOffsetMap);
CSVAccessFixer.run();
}
forceEmptyMetadata(RootFunction);
return Found;
}
bool CPUStateAccessAnalysisPass::runOnModule(Module &Mod) {
CPUStateAccessAnalysis AccessAnalysis(Mod, Variables, Lazy);
return AccessAnalysis.run();
}
char CPUStateAccessAnalysisPass::ID = 0;
using RegisterCPUSAAP = RegisterPass<CPUStateAccessAnalysisPass>;
static RegisterCPUSAAP
X("cpustate-access-analysis", "CPUState Access Analysis Pass", false, false);
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